Load bearing direct drive fan system with variable process control

ABSTRACT

The present invention is directed to a load bearing direct-drive system for driving a fan in a cooling system such as a wet-cooling tower, air-cooled heat exchanger, HVAC system, hybrid cooling tower, mechanical tower or chiller system. The present invention includes a variable process control system that is based on the integration of key features and characteristics such as tower thermal performance, fan speed and airflow, motor torque, fan pitch, fan speed, fan aerodynamic properties, and pump flow. The variable process control system processes feedback signals from multiple locations in order to control a high torque, low variable speed, load bearing motor to drive the fan.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.14/352,050, filed Apr. 15, 2014. The entire disclosure of the aforesaidU.S. application Ser. No. 14/352,050 is hereby incorporated byreference.

This application also claims the benefit of U.S. provisional applicationNo. 62/113,277, filed Feb. 6, 2015. The entire disclosure of applicationNo. 62/113,277 is hereby incorporated by reference.

TECHNICAL FIELD

The present invention generally relates to a method and system forefficiently managing the operation and performance of cooling towers,air-cooled heat exchangers (ACHE), HVAC, and mechanical towers andchillers.

BACKGROUND ART

Industrial cooling systems, such as wet-cooling towers and air-cooledheat exchangers (ACHE), are used to remove the heat absorbed incirculating cooling water used in power plants, petroleum refineries,petrochemical and chemical plants, natural gas processing plants andother industrial facilities. Wet-cooling towers and ACHEs are widelyused in the petroleum refining industry. Refining of petroleum dependsupon the cooling function provided by the wet-cooling towers andair-cooled heat exchangers. Refineries process hydrocarbons at hightemperatures and pressures using processes such as Liquid CatalyticCracking and Isomerization. Cooling water is used to control operatingtemperatures and pressures. The loss of cooling water circulation withina refinery can lead to unstable and dangerous operating conditionsrequiring an immediate shut down of processing units. Wet-cooling towersand ACHEs have become “mission critical assets” for petroleum refineryproduction. Thus, cooling reliability has become mission critical torefinery safety and profit and is affected by many factors such asenvironmental limitations on cooling water usage, environmental permitsand inelastic supply chain pressures and variable refining margins. Asdemand for high-end products such as automotive and aviation fuel hasrisen and refining capacity has shrunk, the refineries have incorporatedmany new processes that extract hydrogen from the lower valueby-products and recombined them into the higher value products. Theseprocesses are dependent on cooling to optimize the yield and quality ofthe product. Over the past decade, many refineries have been addingprocesses that reform low grade petroleum products into higher grade andmore profitable products such as aviation and automotive gasoline. Theseprocesses are highly dependent upon the wet-cooling towers and ACHEs tocontrol the process temperatures and pressures that affect the productquality, process yield and safety of the process. In addition, theseprocesses have tapped a great deal of the cooling capacity reserve inthe towers leaving some refineries “cooling limited” on hot days andeven bottlenecked. ACHE cooling differs from wet cooling towers in thatACHEs depend on air for air cooling as opposed to the latent heat ofvaporization or “evaporative cooling”. Most U.S. refineries operate wellabove 90% capacity and thus, uninterrupted refinery operation iscritical to refinery profit and paying for the process upgradesimplemented over the last decade. The effect of the interruption in theoperation of cooling units with respect to the impact of petroleumproduct prices is described in the report entitled “Refinery Outages:Description and Potential Impact On Petroleum Product Prices”, March2007, U.S. Department of Energy.

Typically, a wet cooling tower system comprises a basin which holdscooling water that is routed through the process coolers and condensersin an industrial facility. The cool water absorbs heat from the hotprocess streams that need to be cooled or condensed, and the absorbedheat warms the circulating water. The warm circulating water isdelivered to the top of the cooling tower and trickles downward overfill material inside the tower. The fill material is configured toprovide a maximum contact surface, and maximum contact time, between thewater and air. As the water trickles downward over the fill material, itcontacts ambient air rising up through the tower either by natural draftor by forced draft using large fans in the tower. Many wet coolingtowers comprise a plurality of cells in which the cooling of water takesplace in each cell in accordance with the foregoing technique. Coolingtowers are described extensively in the treatise entitled “Cooling TowerFundamentals”, second edition, 2006, edited by John C. Hensley,published by SPX Cooling Technologies, Inc.

Many wet cooling towers in use today utilize large fans, as described inthe foregoing discussion, to provide the ambient air. The fans areenclosed within a fan stack which is located on the fan deck of thecooling tower. Fan stacks are typically configured to have a parabolicshape to seal the fan and add fan velocity recovery. In other systems,the fan stack may have a cylindrical shape. Drive systems are used todrive and rotate the fans. The efficiency and production rate of acooling tower is heavily dependent upon the efficiency of the fan drivesystem. The duty cycle required of the fan drive system in a coolingtower environment is extreme due to intense humidity, poor waterchemistry, potentially explosive gases and icing conditions, wind shearforces, corrosive water treatment chemicals, and demanding mechanicaldrive requirements. In a multi-cell cooling tower, such as the typecommonly used in the petroleum industry, there is a fan and fan drivesystem associated with each cell. Thus, if there is a shutdown of themechanical fan drive system associated with a particular cell, then thatcell suffers a “cell outage”. A cell outage will result in a decrease inthe production of refined petroleum. For example, a “cell outage”lasting for only one day can result in the loss of thousands of refinedbarrels of petroleum. If numerous cells experience outages lasting morethan one day, the production efficiency of the refinery can besignificantly degraded. The loss in productivity over a period of timecan be measured as a percent loss in total tower-cooling potential. Asmore cell outages occur within a given time frame, the percent loss intotal tower-cooling potential will increase. This, in turn, willdecrease product output and profitability of the refinery and cause anincrease in the cost of the refined product to the end user. It is notuncommon for decreases in the output of petroleum refineries, even ifslight, to cause an increase in the cost of gasoline to consumers. Thereis a direct relationship between cooling BTUs and Production in barrelsper day (BBL/Day).

One prior art drive system commonly used in wet-cooling towers is acomplex, mechanical fan drive system that utilizes a motor that drives adrive train. The drive train is coupled to a gearbox, gear-reducer orspeed-reducer which is coupled to and drives the fan blades. Referringto FIG. 1, there is shown a portion of a wet-cooling tower 1.Wet-cooling tower 1 utilizes the aforesaid prior art fan drive system.Wet cooling tower 1 has fan stack 2 and fan 3. Fan 3 has fan seal disk4, fan hub 5A and fan blades 5B. Fan blades 5B are connected to fan hub5A. The prior art fan drive system includes a gearbox 6 that is coupledto drive shaft 7 which drives gearbox 6. The prior art fan drive systemincludes induction motor 8 which rotates drive shaft 7. Shaft couplings,not shown but well known in the art, are at both ends of drive shaft 7.These shaft couplings couple the draft shaft 7 to the gearbox 6 and toinduction motor 8. Wet-cooling tower 1 includes fan deck 9 upon whichsits the fan stack 2. Gearbox 6 and induction motor 9 are supported by aladder frame or torque tube (not shown) but which are well known in theart. Vibration switches are typically located on the ladder frame ortorque tube. One such vibration switch is vibration switch 8A shown inFIG. 1. These vibration switches function to automatically shut down afan that has become imbalanced for some reason. This prior art fan drivesystem is subject to frequent outages, a less-than-desirable MTBF (MeanTime Between Failure), and requires diligent maintenance, such asregular oil changes, in order to operate effectively. Coupling and shaftalignment are critical and require experienced craft labor. One exampleof a mechanical drive system used in the prior art gearbox-type fandrive utilizes five rotating shafts, eight bearings, three shaft seals(two at high speed), and four gears (two meshes). This drive trainabsorbs about 3% of the total power. Although this particular prior artfan drive system may have an attractive initial low cost, cooling towerend-users found it necessary to purchase heavy duty and oversizedcomponents such as composite gearbox shafts and couplings in order toprevent breakage of the fan drive components especially when attemptingacross-the-line starts. Many cooling tower end-users also added otheroptions such as low-oil shutdown, anti-reverse clutches and oil bathheaters. Thus, the life cycle cost of the prior art mechanical fan drivesystem compared to its initial purchase price is not equitable. Once theend user has purchased the more expensive heavy duty and oversizedcomponents, the reliability of the prior art fan drive system is stillquite poor even after they perform all the expensive and time consumingmaintenance. Thus, this prior art gearbox-type drive system has a low,initial cost, but a high cycle cost with poor reliability. In amulti-cell cooling tower, such as the type commonly used in thepetroleum industry, there is a fan and prior art mechanical fan drivesystem associated with each cell. Thus, if there is a shutdown of themechanical fan drive system associated with a particular cell, then thatcell suffers a “cell outage” which was described in the foregoingdescription. The loss in productivity over a period of time due to thepoor reliability of the prior art mechanical fan drive systems can bemeasured as a percent loss in refinery production (bbls/day). In onecurrently operating cooling tower system, data and analysis has shownthat the loss of one cell is equated to the loss of 2,000 barrels perday.

The problems and inefficiencies of gear-box type drive systems used todrive paper machines has been documented in the article entitled“Permanent Magnet Motors Eliminate Gearboxes”, by Jouni Ikäheimo,published in ABB Review, Jan. 1, 2002. The article describes replacinggear-box type drive systems for paper machines with permanent magnetmotors. However, the permanent magnet motors described in this articleare not load bearing motors and cannot bear the loads of a cooling towerfan or the loads of a fan in an air-cooled heat exchanger tower.Furthermore, this article neither discloses the problems associated withthe use of gear-box type drive systems in wet cooling towers nordiscloses a solution for such problems.

Other types of prior art fan drive systems, such as V-belt drivesystems, also exhibit many problems with respect to maintenance, MTBFand performance and do not overcome or eliminate the problems associatedwith the prior art gearbox-type fan drive systems. One attempt toeliminate the problems associated with the prior art gearbox-type fandrive system was the prior art hydraulically driven fan systems. Such asystem is described in U.S. Pat. No. 4,955,585 entitled “HydraulicallyDriven fan System for Water Cooling Tower”.

Air Cooled Heat Exchangers (ACHE) are well known in the art and are usedfor cooling in a variety of industries including power plants, petroleumrefineries, petrochemical and chemical plants, natural gas processingplants, and other industrial facilities that implement energy intensiveprocesses. ACHE exchangers are used typically where there is lack ofwater, or when water-usage permits cannot be obtained. ACHEs lack thecooling effectiveness of “Wet Towers” when compared by size (a.k.a.footprint). Typically, an ACHE uses a finned-tube bundle. Cooling air isprovided by one or more large fans. Usually, the air blows upwardsthrough a horizontal tube bundle. The fans can be either forced orinduced draft, depending on whether the air is pushed or pulled throughthe tube bundle. Similar to wet cooling towers, fan-tip speed typicallydoes not exceed 12,000 feet per minute for aeromechanical reasons andmay be reduced to obtain lower noise levels. The space between thefan(s) and the tube bundle is enclosed by a fan stack that directs theair (flow field) over the tube bundle assembly thereby providingcooling. The whole assembly is usually mounted on legs or a pipe rack.The fans are usually driven by a fan drive assembly that uses anelectric motor. The fan drive assembly is supported by a steel,mechanical drive support system. Vibration switches are typicallylocated on the structure that supports the fan assembly. These vibrationswitches function to automatically shut down a fan that has becomeimbalanced for some reason. Airflow is very important in ACHE cooling toensure that the air has the proper “flow field” and velocity to maximizecooling. Turbulence caused by current fan gear support structure canimpair cooling efficiency. Therefore, mass airflow is the key parameterto removing heat from the tube and bundle system. ACHE cooling differsfrom wet cooling towers in that ACHEs depend on air for air cooling asopposed to the latent heat of vaporization or “evaporative cooling”.

Prior art ACHE fan drive systems use any one of a variety of fan drivecomponents. Examples of such components include electric motors, steamturbines, gas or gasoline engines, or hydraulic motors. The most commondrive device is the electric motor. Steam and gas drive systems havebeen used when electric power is not available. Hydraulic motors havealso been used with limited success. Specifically, although hydraulicmotors provide variable speed control, they have relatively lowefficiencies. Motor and fan speed are sometimes controlled with variablefrequency drives with mixed success. The most commonly used speedreducer is the high-torque, positive type belt drive, which usessprockets that mesh with the timing belt cogs. They are used with motorsup to 50 or 60 horsepower, and with fans up to about 18 feet indiameter. Banded V-belts are still often used in small to medium sizedfans, and gear drives are used with very large motors and fan diameters.Fan speed is set by using a proper combination of sprocket or sheavesizes with timing belts or V-belts, and by selecting a proper reductionratio with gears. In many instances, right-angle gear boxes are used aspart of the fan drive system in order to translate and magnify torquefrom an offset electrical motor. However, belt drives, pulleys andright-angle gear boxes have poor reliability. The aforesaid complex,prior art mechanical drive systems require stringent maintenancepractices to achieve acceptable levels of reliability. In particular,one significant problem with ACHE fan systems is the poor reliability ofthe belt due to belt tension. A common practice is to upgrade to “timingbelts” and add a tension system. One technical paper, entitled“Application of Reliability Tools to Improve V-Belt Life on Fin FanCooler Units”, by Rahadian Bayu of PT, Chevron Pacific Indonesia, Riau,Indonesia, presented at the 2007 International Applied ReliabilitySymposium, addresses the reliability and efficiency of V-belts used inmany prior art fan drive systems. The reliability deficiencies of thebelt and pulley systems and the gear reducer systems used in the ACHEfan drive systems often result in outages that are detrimental tomission critical industries such as petroleum refining, petro-chemical,power generation and other process intensive industries dependent oncooling. Furthermore, the motor systems used in the ACHE fan drivesystems are complex with multiple bearings, auxiliary oil andlubrications systems, complex valve systems for control and operation,and reciprocating parts that must be replaced at regular intervals. Manypetroleum refineries, power plants, petrochemical facilities, chemicalplants and other industrial facilities utilizing prior art ACHE fandrive systems have reported that poor reliability of belt drive systemsand right-angle drive systems has negatively affected production output.These industries have also found that service and maintenance of thebelt drive and gearbox system are major expenditures in the life cyclecost, and that the prior art motors have experienced failure due to theincorrect use of high pressure water spray. The duty cycle required ofan ACHE fan drive system is extreme due to intense humidity, dirt andicing conditions, wind shear forces, water washing (because the motorsare not sealed, sometime they get sprayed by operators to improvecooling on hot days), and demanding mechanical drive requirements.

In an attempt to increase the cooling performance of ACHE coolingsystems, some end-users spray water directly on the ACHE system toprovide additional cooling on process limiting, hot days. Furthermore,since fan blades can become “fouled” or dirty in regular service andlose performance, many end-users water-wash their ACHE system tomaintain their cooling performance. However, directly exposing the ACHEsystem to high pressure water spray can lead to premature maintenanceand/or failure of system components, especially since prior art drivesystems are typically open thereby allowing penetration by water andother liquids. Thus, the efficiency and production rate of a process isheavily dependent upon the reliability of the ACHE cooling system andits ability to remove heat from the system.

Prior art fan systems have further drawbacks. Most of the currentlyinstalled fleet of cooling tower fans operates continuously at 100%speed. For a small percentage of applications, variable frequency drives(“VFD”) of Adjustable Speed Drives have been applied to an inductionmotor to simulate variable speed. However, the application of VFDs toinduction motors has not been overly successful and not implemented on awide scale due to poor success rates. In some cases this may alsoinvolve a two-speed induction motor. These applications have not beenwidely installed by end-users. In some cases, end-users have installedVFDs solely to provide “soft starts” to the system thereby avoiding“across the line starts” that can lead to failure or breakage of thegearbox system when maximum torque is applied to the system at start-up.This issue is further exacerbated by “fan windmilling” which occurs whenthe fan turns in reverse due to the updraft force of the tower on thepitch of the fan. Windmilling of the fan is not allowed due to thelubrication limitation of gearboxes in reverse and requires the additionof an anti-reverse mechanism.

Prior art variable speed induction motors are reactive to basintemperature and respond by raising the fan to 100% fan tip speed untilbasin temperature demand is met and then reducing the speed to apredetermined set speed which is typically 85% fan tip speed. Suchsystems utilize lagging feedback loops that result in fan speedoscillation, instability and speed hunting which consumes large amountsof energy during abrupt speed changes and inertial changes which resultsin premature wear and failure of gear train parts that are designed forsingle speed, omni-direction operation.

Induction motors in variable speed duty require extra insulation,additional windings and larger cooling fans for part-load cooling whichincreases the cost and size. Application of induction motors on variablespeed fans requires that the motor be able to generate the requiredtorque to turn the fan to speed at part-load operation which can alsorequire the motor to be larger than for a steady state application andthus increase the cost and size. In these variable speed fan systems,the fan speed is controlled by the basin temperature set point. Thismeans that fan speed will increase according to a set algorithm when thebasin temperature exceeds a temperature set point in order to cool thebasin water. Once the basin temperature set point has been satisfied thefan speed will be reduced according to the programmed algorithms.Furthermore, motors and gearboxes are applied without knowledge of thecooling tower thermal performance and operate only as a function of thebasin temperature set point which results in large speed swings of thefan wherein the fan speed is cycled from minimum fan speed to maximumfan speed over a short period of time. The speed swings that occur atmaximum fan acceleration consume significant amounts of energy.

Typical prior art gearboxes are designed for one-way rotation asevidenced by the lube system and gear mesh design. These gearboxes werenever intended to work in reverse. In order to achieve reverse rotation,prior art gearboxes were modified to include additional lube pumps inorder to lubricate in reverse due to the design of the oil slingerlubrication system which is designed to work in only one direction.These lube pumps are typically electric but can also be of otherdesigns. The gear mesh of the gearbox is also a limiting factor forreverse rotation as the loading on the gear mesh is not able to bear thedesign load in reverse as it can in forward rotation. Typically, themodified gearboxes could operate in reverse at slow speed for no morethan two minutes. End users in colder climates that require reverserotation for de-icing the cooling tower on cold days have reportednumerous failures of the gearbox drive train system. In addition, mostoperators have to manually reverse the system on each cell which mayinclude an electrician. Since the gearbox and lubrication system aredesigned for one-way rotation typically at 100% fan speed, fan braking,gear train inertia and variable speed duty will accelerate wear and tearon the gearbox, drive shaft and coupling components as the inertialloads are directly reacted into the drive train, gearbox and motor.

VFDs have been and are being applied to induction motors and fan gearboxsystems with the hope of saving energy. However, these modificationsrequire more robust components to operate the fan based upon the basintemperature set point. The DOE (Department of Energy) reports that theaverage energy savings of such applications is 27%. This savings isdirectly proportional to the fan laws and the reduced loading on thesystem as opposed to motor efficiency, which for an induction motor,drops off significantly in part-load operation.

Currently operating cooling towers typically do not use expensivecondition-monitoring equipment that has questionable reliability andwhich has not been widely accepted by the end users. Vibration safety inprior art fan systems is typically achieved by the placement ofvibration switches on the ladder frame near the motor. An example ofsuch a vibration switch is vibration switch 8A shown in FIG. 1. Thesevibration switches are isolated devices and are simply on-off switchesthat do not provide any kind of external signals or monitoring. Thesevibration switches have poor reliability and are poorly applied andmaintained. Thus, these vibration switches provide no signals orinformation with respect to fan system integrity. Therefore, it is notpossible to determine the source or cause of the vibrations. Suchvibration switches are also vulnerable to malfunction or poorperformance and require frequent testing to assure they are working. Thepoor reliability of these vibration switches and their lack of fidelityto sense an impeding blade failure continues to be a safety issue.

In prior art multi-cell cooling systems that utilize a plurality fanswith gearbox drives, each fan is operated independently at 100%, orvariable speed controlled independently by the same algorithm. Coolingtowers are typically designed at one design point: maximum hot daytemperature, maximum wet-bulb temperature and thus operate the fans at100% steady state to satisfy the maximum hot day temperature, maximumwet-bulb temperature design condition, regardless of environmentalconditions.

Current practice (CTI and ASME) attempts to measure the cooling towerperformance to a precision that is considered impractical for anoperating system that is constantly changing with the surroundingtemperature and wet-bulb temperature. Most refinery operators operatewithout any measure of performance and therefore wait too long betweenservice and maintenance intervals to correct and restore the performanceof the cooling tower. It is not uncommon for some end-users to operatethe tower to failure. Some end-users test their cooling towers forperformance on a periodic basis, typically when a cooling tower isexhibiting some type of cooling performance problem. Such tests can beexpensive and time consuming and typically normalize the test data tothe tower design curve. Furthermore, these tests do not provide anytrending data (multiple test points), load data or long-term data toestablish performance, maintenance and service criteria. For example,excessive and wasted energy consumption occurs when operating fans thatcannot perform effectively because the fill is clogged thus allowingonly partial airflow through the tower. Poor cooling performance resultsin degraded product quality and/or throughput because reduced cooling isnegatively affecting the process. Poor cooling tower performance canresult in unscheduled downtime and interruptions in production. In manyprior art systems, it is not uncommon for end-users to incorrectlyoperate the cooling tower system by significantly increasing electricalpower to the fan motors to compensate for a clogged tower or to increasethe water flow into the tower to increase cooling when the actualcorrective action is to replace the fill in the tower. Poor coolingtower performance can lead to incorrect operation and has many negativeside effects such as reduced cooling capability, poor reliability,excessive energy consumption, poor plant performance, and decrease inproduction and safety risks.

Therefore, in order to prevent supply interruption of the inelasticsupply chain of refined petroleum products, the reliability andsubsequent performance of wet-cooling towers and ACHE cooling systemsmust be improved and managed as a key asset to refinery safety,production and profit.

What is needed is a method and system that allows for the efficientoperation and management of fans in wet-cooling towers and dry-coolingapplications.

DISCLOSURE OF THE INVENTION

In one aspect, the present invention is directed to a system and methodfor efficiently managing the operation of fans in a cooling tower systemincluding wet-cooling towers, air-cooled heat exchangers (ACHE),mechanical towers, hybrid cooling towers, hybrid heat exchangers, HVACsystems and chillers. The present invention is based on the integrationof the key features and characteristics such as (1) tower thermalperformance, (2) fan speed and airflow, (3) motor torque, (4) fan pitch,(5) fan speed, (6) fan aerodynamic properties, and (7) pump flow.

The present invention is directed to a load bearing, direct drive fansystem and variable process control system for efficiently operating afan in a wet-cooling tower, air-cooled heat exchanger (ACHE), HVACsystem, mechanical tower, hybrid cooling tower, hybrid heat exchangerand chiller. The present invention is based on the integration of thekey characteristics such as tower thermal performance, fan speed andairflow, motor torque, fan pitch, fan speed, fan aerodynamic properties,and pump flow rate. As used herein, the term “pump flow rate” refers tothe flow rate of cooled process liquids that are pumped from the coolingtower for input into an intermediate device, such as condenser, and thento the process, then back to the intermediate device and then back tothe cooling tower. The present invention uses a variable process controlsystem wherein feedback signals from multiple locations are processed inorder to control high-torque, low variable speed, load bearing motorsthat drive the fans and pumps. Such feedback signals represent certainoperating conditions including motor temperature, basin temperature,vibrations and pump flow-rate. Thus, the variable process control systemcontinually adjust motor RPM, and hence fan and pump RPM, as theoperators or users change or vary turbine back-pressure set point,condenser temperature set point process signal (e.g. crude cracker), andplant part-load setting. The variable process control processes thesefeedback signals to optimize the plant for cooling and to preventequipment (turbine) failure or trip. The variable process control alertsthe operators for the need to conduct maintenance actions to remedydeficient operating conditions such as condenser fouling. The variableprocess control of the present invention increases cooling for crackingcrude and also adjusts the motor RPM, and hence fan and pump RPM,accordingly during plant part-load conditions in order to save energy.

In accordance with the present invention, a load bearing, direct-drivesystem is used to rotate the fan. The load bearing, direct-drive systemcomprises a high-torque, low variable speed, load bearing electricmotor. The high-torque, low variable speed, load bearing electric motorhas a rotatable shaft that is directly connected to fan or fan hub. Inone embodiment, the high-torque, low variable speed, load bearingelectric motor comprises a permanent magnet motor. In anotherembodiment, the high-torque, low variable speed, load bearing electricmotor comprises a synchronous reluctance motor. In other embodiments,other types of high-torque, low variable speed, load bearing electricmotors are used.

The variable process control system of the present invention comprises acomputer system that comprises a data acquisition device, referred to asDAQ device 200 in the ensuing description. The computer system furthercomprises an industrial computer, referred to as industrial computer 300in the ensuing description.

The variable process control system of the present invention includes aplurality of variable speed pumps, wherein each variable speed pumpscomprises a high torque, low variable speed, load bearing, electricmotor. The variable process control system further comprises a VariableFrequency Drive (VFD) device which comprises a plurality of individualVariable Frequency Drives. Each Variable Frequency drive is dedicated toone high torque, low variable speed, load bearing electric motor.Therefore, one Variable Frequency Drive corresponds to the high torque,low variable speed, load bearing electric motor that drives the fan, andeach of the remaining Variable Frequency Drives is dedicated tocontrolling the high torque, low variable speed, load bearing electricmotor of a corresponding variable speed pump. Thus, each motor iscontrolled independently. In an alternate embodiment, Variable SpeedDrives (VSD) are used instead of variable frequency drive devices.

The variable process control system of the present invention providesadaptive and autonomous variable speed operation of the fan and pumpwith control, supervision and feedback with operator override. Acomputer system processes data including cooling tower basintemperature, current process cooling demand, condenser temperatureset-point, tower aerodynamic characteristics, time of day, wet-bulbtemperature, vibration, process demand, environmental stress (e.g. windspeed and direction) and historical trending of weather conditions tocontrol the variable speed fan in order to control the air flow throughthe cooling tower and meet thermal demand. The Variable Process ControlSystem anticipates process demand and increases or decreases the fanspeed in pattern similar to a sine wave over a twenty four (24) hourperiod. The Variable Process Control System accomplishes this by using aRunge-Kutter algorithm (or similar algorithm) that analyzes historicalprocess demand and environmental stress as well as current processdemand and current environmental stress to minimize the energy used tovary the fan speed. This variable process control of the presentinvention is adaptive and learns the process cooling demand byhistorical trending as a function of date and time. The operators of theplant input basin temperature set-point data into the Plant DCS(Distributed Control System). The basin temperature set-point data canbe changed instantaneously to meet additional cooling requirements suchas cracking heavier crude, maintaining vacuum backpressure in a steamturbine, preventing heat exchanger fouling or derating the plant topart-load. In response to the change in the basin temperature set-point,the variable process control system of the present inventionautomatically varies the rotational speed of the high torque, lowvariable speed, load bearing electric motor, and hence the rotationalspeed of the fan, so that the process liquids are cooled such that thetemperature of the liquids in the collection basin is substantially thesame as the new basin temperature set-point. This feature is referred toherein as “variable process control”.

In an alternate embodiment, a condenser temperature set-point isinputted into the plant Distributed Control System (DCS) by theoperators. The DCS is in electronic signal communication with the DataAcquisition (DAQ) Device and/or Industrial Computer of the VariableProcess Control System of the present invention. The Data Acquisitiondevice then calculates a collection basin temperature set-point that isrequired in order to meet the condenser temperature set-point. TheVariable Process Control system then operates the fan and variable speedpumps to maintain a collection basin temperature that meets thecondenser temperature set-point inputted by the operators.

The variable process control system of the present invention utilizesvariable speed motors to drive fans and pumps to provide the requiredcooling to the industrial process even as the environmental stresschanges. Process parameters, including but not limited to, temperatures,pressures and flow rates are measured throughout the system in order tomonitor, supervise and control cooling of liquids (e.g. water) used bythe industrial process. The variable process control system continuallymonitors cooling performance as a function of process demand andenvironmental stress to determine available cooling capacity that can beused for additional process production (e.g. cracking of crude, hot-dayturbine output to prevent brown-outs) or identify cooling towerexpansions. The variable process control system automatically adjustscooling capacity when the industrial process is at part-load conditions(e.g. outage, off-peak, cold day, etc.)

The present invention is applicable to multi-cell cooling towers. In amulti-cell system, the speed of each fan in each cell is varied inaccordance with numerous factors such as Computational Liquid DynamicAnalysis, thermal modeling, tower configuration, environmentalconditions and process demand.

The core relationships upon which the system and method of the presentinvention are based are as follows:

-   -   A) Mass airflow (ACFM) is directly proportional to fan RPM;    -   B) Fan Static Pressure is directly proportional to the square of        the fan RPM; and    -   C) Fan Horsepower is directly proportional to the cube of the        fan RPM.

The system of the present invention determines mass airflow by way ofthe operation of the high torque, low variable speed, load bearingmotor. The variable process control system of the present inventionincludes a plurality of pressure devices that are located in the coolingtower plenum. The data signals provided by these pressure devices, alongwith the fan speed data from the VFD, fan pitch and the fan map, areprocessed by an industrial computer and used to determine the massairflow in the fan cell.

The variable process control system of the present invention monitorscooling tower performance in real time and compares the performance datato design data in order to formulate a performance trend over time. Thevariable process control system of the present invention utilizes“trending” in order to revise, adjust and optimize the fan variablespeed schedule, and plan and implement cooling tower service,maintenance and improvements as a function of process loading, such ashot day or cold day limitations, or selection of the appropriate fill tocompensate for poor water quality. The variable process control systemof the present invention utilizes long term trending to achieve trueperformance prediction as opposed to periodic testing which is done inprior art systems.

The present invention is a unique, novel and reliable approach todetermining cooling tower performance. The present invention uses fanhorsepower and motor current draw (i.e. amperes) in conjunction with ameasured plenum pressure. The measured plenum pressure equates to faninlet pressure. The present invention uses key parameters measured bythe system including measured plenum pressure in combination with thefan speed, known from the VFD (Variable Frequency Drive), and the designfan map to determine mass airflow and real time cooling performance. Theplenum pressure is measured by at least one pressure device that islocated in the fan deck. The variable process control system of thepresent invention recognizes poor performance conditions and generateswarnings or alerts that prompt end-users to perform inspections andidentify the required corrective actions.

The design criteria of the variable process control system of thepresent invention are based upon the thermal design of the tower, theprocess demand, environmental conditions and energy optimization. On theother hand, the prior art variable speed fan gearbox systems are appliedwithout knowledge of the tower thermal capacity and are only controlledby the basin temperature set-point.

A very important feature of the high-torque, low variable speed, loadbearing electric motor of the present invention is that it may be usedin new installations (e.g. new tower constructions or new fan assembly)or it can be used as a “drop-in” replacement. If the high-torque, lowvariable speed, load bearing electric motor is used as a “drop-in”replacement, it will easily interface with all existing fans and fanhubs and provide the required torque and speed to rotate all existingand possible fan configurations within the existing “installed” weightand fan height requirements.

The variable process control system of the present invention isprogrammed to operate based on the aforesaid criteria as opposed toprior art systems which are typically reactive to the basin temperature.Airflow generated by the variable process control system of the presentinvention is a function of fan blade pitch, fan efficiency and fan speedand is optimized for thermal demand (100% cooling) and energyconsumption. Thermal demand is a function of the process. The variableprocess control system of the present invention anticipates coolingdemand based upon expected seasonal conditions, historical andenvironmental conditions, and is designed for variable speed, autonomousoperation with control and supervision.

Since the high-torque, low variable speed, load bearing electric motorthat drives the fan delivers constant high torque throughout itsvariable speed range, the fan pitch is optimized for expected hot-dayconditions (max cooling) and maximum efficiency based on the expectedand historical weather patterns and process demand of the plantlocation. With the aforementioned constant high-torque, increasedairflow is achieved with greater fan pitch at slower speeds therebyreducing acoustic signature or fan noise in sensitive areas.

The variable process control system of the present invention alsoprovides capability for additional airflow or cooling for extremely hotdays and is adaptive to changes in process demand. The variable processcontrol system of the present invention can also provide additionalcooling to compensate for loss of a cooling cell in a multi-cell tower.This mode of operation of the variable process control system isreferred herein to the “Compensation Mode”. In the Compensation Mode,the fan speed of the remaining cells is increased to produce theadditional flow through the tower to compensate for the loss of coolingresulting from the lost cells. The variable process control system ofthe present invention is programmed not to increase the fan speedgreater than the fan tip speed when compensating for the loss of coolingresulting from the loss cell. The compensation mode feature is designedand programmed into the variable process control system of the presentinvention based upon the expected loss of a cell and its location in thetower. The variable process control system of the present inventionvaries the speed of the fans in the remaining cells in accordance withthe configuration, geometry and flow characteristic of the cooling towerand the effect each cell has on the overall cooling of the coolingtower. This provides the required cooling and manages the resultantenergy consumption of the cooling tower. The variable process controlsystem of the present invention manages the variable speed of the motorin each cell thereby providing required cooling while optimizing energyconsumption based upon the unique configuration and geometry of eachcooling tower.

Operational characteristics of the variable process control system ofthe present invention include:

-   -   1) autonomous variable speed operation based on process demand,        thermal demand, cooling tower thermal design and environmental        conditions;    -   2) adaptive cooling that provides (a) regulated thermal        performance based upon an independent parameter or signal such        as lower basin temperature to improve cracking of heavier crude        during a refining process, (b) regulated temperature control to        accommodate steam turbine back-pressure in a power plant for        performance and safety and (c) regulated cooling to prevent        condenser fouling;    -   3) fan idle in individual cells of a multi-cell tower based on        thermal demand and unique cooling tower design (i.e. fan idle)        if thermal demand needs have been met;    -   4) real-time feedback;    -   5) operator override for stopping or starting the fan, and        controlling basin temperature set-point for part-load operation;    -   6) uses fan speed, motor current, motor horsepower and plenum        pressure in combination with environmental conditions such as        wind speed and direction, temperature and wet-bulb temperature        to measure and monitor fan airflow and record all operating        data, process demand trend and environmental conditions to        provide historical analysis for performance, maintenance        actions, process improvements and expansions;    -   7) vibration control which provides 100% monitoring, control and        supervision of the system vibration signature with improved        signature fidelity that allows system troubleshooting, proactive        maintenance and safer operation (post processing);    -   8) vibration control that provides 100% monitoring, control and        supervision for measuring and identifying system resonances in        real time within the variable speed range and then locking them        out of the operating range;    -   9) vibration control that provides 100% monitoring, control and        supervision for providing post processing of vibration        signatures using an industrial computer and algorithms such as        Fast Fourier Transforms (FFT) to analyze system health and        provide system alerts to end users such as fan imbalance as well        control signals to the DAQ (data acquisition) device in the case        of operating issues such as impending failure;    -   10) provides for safe Lock-Out, Tag-Out (LOTO) of the fan drive        system by controlling the deceleration of the fan and holding        the fan at stop while all forms of energy are removed from the        cell including cooling water to the cell so as to prevent an        updraft that could cause the fan to windmill in reverse;    -   11) provides for a proactive maintenance program based on actual        operating data, cooling performance, trending analysis and post        processing of data using a Fast Fourier Transform to identify        issues such as fan imbalance, impending fan hub failure,        impending fan blade failure and provide service, maintenance and        repair and replacement before a failure leads to a catastrophic        event and loss of life, the cooling asset and production.    -   12) provides a predictive maintenance program based on actual        operating data, cooling performance, trending analysis and        environmental condition trending in order to provide planning        for cooling tower maintenance on major cooling tower subsystems        such as fill replacement and identify cooling improvements for        budget creation and planning for upcoming outages;    -   13) monitoring capabilities that alert operators if the system        is functioning properly or requires maintenance or an        inspection;    -   14) operator may manually override the variable control system        to turn fan on or off;    -   15) provides an operator with the ability to adjust and fine        tune cooling based on process demand with maximum hot-day        override;    -   16) monitors auxiliary systems, such as pumps, to prevent        excessive amounts of water from being pumped into the tower        distribution system which could cause collapse of the cooling        tower;    -   17) continuously measures current process demand and        environmental stress;    -   18) varies the fan speed in gradual steps as the variable        process control system learns from past process cooling demand        as a function season, time, date and environmental conditions to        predict future process demand, wherein the variation of fan        speed in gradual steps minimizes energy draw and system wear;    -   19) the high-torque, low variable speed, load bearing electric        motor is not limited in reverse operation thereby allowing the        use of regenerative drive options to provide power to the grid        when fans are windmilling in reverse;    -   20) automatic deicing; and    -   21) the high-torque, low variable speed, load bearing electric        motor has the same characteristics in reverse operation as it        does in forward operation.

In one aspect, the present invention is directed to a wet-cooling towersystem comprising a load bearing, direct drive fan system and anintegrated variable process control system. The wet-cooling tower systemcomprises a wet-cooling tower that comprises a tower structure that hasfill material located within the tower structure, a fan deck locatedabove the fill material, and a collection basin located beneath the fillmaterial for collecting cooled liquid. A fan stack is positioned uponthe fan deck and a fan is located within the fan stack. The fancomprises a hub to which are connected a plurality of fan blades. Theload bearing, direct drive fan system comprises a high-torque, lowvariable speed, load bearing, electric motor that has a rotatable shaftconnected to the hub. In one embodiment, the high-torque, low variablespeed, load bearing, electric motor has a rotational speed between 0 RPMand about 250 RPM. In another embodiment, the high-torque, low variablespeed, load bearing, electric motor is configured to have rotationalspeeds that exceed 500 RPM. The high-torque, low variable speed, loadbearing, electric motor is sealed and comprises a rotor, a stator and acasing. The rotor and stator are located within the casing. The variableprocess control system comprises a variable frequency drive device thatis in electrical signal communication with the high-torque, low variablespeed, load bearing, electric motor to control the rotational speed ofthe motor. The variable frequency drive device comprises a variablefrequency controller that has an input for receiving AC power and anoutput for providing electrical signals that control the operationalspeed of the motor, and a signal interface in electronic data signalcommunication with the variable frequency controller to provide controlsignals to the variable frequency controller so as to control the motorRPM and to provide output motor status signals that represent the motorspeed, motor current draw, motor voltage, motor torque and the totalmotor power consumption. The variable process control system furthercomprises a data acquisition device in electrical signal communicationwith the signal interface of the variable frequency drive device forproviding control signals to the variable frequency drive device and forreceiving the motor status signals. The wet-cooling tower system furthercomprises a pair of vibration sensors that are in electrical signalcommunication with the data collection device. Each vibration sensor islocated within the motor casing where it is protected from theenvironment and positioned on a corresponding motor bearing structure.As a result of the structure and design of the high torque, low variablespeed, load bearing electric motor and the direct connection of themotor shaft to the fan or fan hub, the resultant bearing system is stout(stiff and damped) and therefore results in a very smooth system withlow vibration. In an alternate embodiment, at least one additionalvibration sensor is attached to the exterior of the motor casing orhousing.

In comparison to the prior art, the vibration signature of the hightorque, low variable speed, load bearing electric motor has a lowamplitude with clear signature fidelity which allows for proactiveservice and maintenance and an improvement in safety and production.Trending of past cooling tower operation and post processing, vibrationsignal analysis (FFT) determines whether other vibration signatures areindicating such issues as a fan blade imbalance, fan blade pitchadjustment, lubrication issues, bearing issues and impending fan hub,fan blade and motor bearing failure, which are major safety issues. Thelocation of the vibration sensors on the motor bearings also allows forprogramming of lower amplitude shut-off parameters.

As described in the foregoing description, the variable process controlsystem of the present invention comprises a plurality of vibrationsensors that may include accelerometers, velocity and displacementtransducers or similar devices to monitor, supervise and controlvibration characteristics of the direct drive fan system and the directdrive pump system that pumps water to and from the cooling tower. Thesevibration sensors detect various regions of the motor and fan frequencyband that are to be monitored and analyzed.

The present invention has significantly less “frequency noise” becausethe present invention eliminates ladder frames, torque tubes, shafts,couplings, gearboxes and gearmesh that are commonly used in prior artsystems. In accordance with the invention, vibration sensors are locatedat the bearings of the high-torque, low variable speed, load bearingmotor. Each vibration sensor outputs signals representing vibrations ofthe motor bearings. Thus, vibrations that are directly coupled to thefan or fan system are read directly at the bearings as opposed to theprior art technique of measuring the vibrations at the ladder frame. Asa result of this important feature of the invention, the presentinvention can identify, analyze and correct for changes in theperformance of the fan, thereby providing a longer running system thatis relatively safer.

The variable process control system of the present invention furthercomprises a plurality of temperature sensors in electrical signalcommunication with the data collection device. The present inventionutilizes external temperature sensors that measure the temperature ofthe exterior of the motor casing or housing and internal temperaturesensors located within the casing or housing of the motor to measure thetemperature within the casing, the temperature of the stator and coilwindings. At least one temperature sensor is located in the basin tomeasure temperature of liquid (e.g. water) within the basin. Temperaturesensors also measure the environmental temperature (e.g. ambienttemperature). Another temperature sensor measures the temperature of theair in the fan stack before the fan. The variable process control systemof the present invention further includes at least one pressure sensorlocated in the fan deck that measures the pressure in the fan plenum,which equates to the pressure at the fan inlet. The variable processcontrol system further comprises a computer in data signal communicationwith the data collection device. The computer comprises a memory and aprocessor to process the signals outputted by the vibration andtemperature sensors and to also process the pump flow signals and themotor status signals. The computer outputs control signals to the datacollection device for routing to the variable frequency drive device inorder to control the speed of the motor in response to the processing ofthe sensor signals.

The variable process control system also includes a leak detector probefor detecting leakage of gasses from heat exchanges and other equipment.

Some key features of the system of the present invention are:

-   1) reverse, de-ice, flying-start and soft-stop modes of operation    with infinite control of fan speed in both reverse and forward    directions;-   2) variable process control, refining and power generation;-   3) capability of part-load operation;-   4) maintaining vacuum backpressure for a steam turbine and crude    cracking;-   5) prevents damage and fouling of heat exchangers, condensers and    auxiliary equipment;-   6) line-replaceable units such as hazardous gas monitors, sensors,    meter(s) or probes are integrated into the motor casing (or housing)    to detect and monitor fugitive gas emissions in the fan air-steam    accordance with the U.S. EPA (Environmental Protection Agency)    regulations;-   7) variable speed operation with low, variable speed capability;-   8) cells in multi-cell tower can be operated independently to meet    cooling and optimize energy;-   9) 100% monitoring, autonomous control and supervision of the    system;-   10) automated and autonomous operation;-   11) relatively low vibrations and high vibration fidelity due to    system architecture and structure;-   12) changes in vibration signals are detected and analyzed using    trending data and post processing;-   13) vibration sensors are integrated into the motor and thus    protected from the surrounding harsh, humid environment;-   14) uses a variable frequency drive (VFD) device that provides    signals representing motor torque and speed;-   15) uses DAQ (data acquisition) device that collects signals    outputted by the VFD and other data signals;-   16) uses a processor that processes signals collected by the DAQ    device, generates control signals, routes control signals back to    VFD and implements algorithms (e.g. FFT) to process vibration    signals;-   17) uses mechanical fan-lock that is applied directly to the shaft    of the motor to prevent rotation of the fan when power is removed    for maintenance and hurricane service;-   18) uses a Lock-Out-Tag-Out (LOTO) procedure wherein the fan is    decelerated to 0.0 RPM under power and control of the motor and VFD    and the motor holds the fan at 0.0 RPM while a mechanical lock    device is applied to the motor shaft to prevent rotation of the fan,    and then all forms of energy are removed per OSHA Requirements for    Service, Maintenance and Hurricane Duty (e.g. hurricane, tornado,    shut-down, etc.);-   19) produces regenerative power when the fan is windmilling;-   20) the motor and VFD provide infinite control of the fan    acceleration and can hold the fan at 0.0 RPM, and also provide fan    deceleration and fan rotational direction;-   21) allows fan to windmill in reverse due to cooling water updraft;-   22) the high-torque, low variable speed, load bearing electric motor    can operate in all systems, e.g. wet-cooling towers, ACHEs, HVAC    systems, chillers, blowers, etc.;-   24) the high-torque, low variable speed, load bearing electric motor    directly drive the fan and pumps; and-   25) the high-torque, low variable speed, load bearing electric motor    can be connected to a fan hub of a fan, or directly connected to a    one-piece fan.

BRIEF DESCRIPTION OF THE DRAWINGS

Although the scope of the present invention is much broader than anyparticular embodiment, a detailed description of the preferredembodiments follows together with illustrative figures, wherein likereference numerals refer to like components, and wherein:

FIG. 1 is a side view, in elevation, of a wet-cooling tower that uses aprior art fan drive system;

FIG. 2 is a block diagram of a variable process control system inaccordance with one embodiment of the present invention, wherein thevariable process control system controls the operation of a coolingtower;

FIG. 3 is a diagram of the feedback loops of the system of FIG. 2;

FIG. 4 is a block diagram illustrating the interconnection of apermanent magnet motor, data acquisition device and variable frequencydrive device, all of which being shown in FIG. 2;

FIG. 5A is a diagram showing the internal configuration of the permanentmagnet motor shown in FIG. 4, the diagram specifically showing thelocation of the bearings of the permanent magnet motor;

FIG. 5B is a diagram showing a portion of the permanent magnet motor ofFIG. 5A, the diagram showing the location of the accelerometers withinthe motor housing;

FIG. 6 is a plot of motor speed versus horsepower for the high torque,low variable speed, load bearing permanent magnet motor used in directdrive fan system of the present invention;

FIG. 7 is a graph illustrating a comparison in performance between theload bearing, direct drive fan system of the present invention and aprior art gearbox-type fan drive system that uses a variable speedinduction motor;

FIG. 8 is a side view, in elevation and partially in cross-section, of awet-cooling tower employing the load bearing, direct drive fan system ofthe present invention;

FIG. 9 is a graph showing a fan speed curve that is similar to a sinewave and represents the increase and decrease in the fan speed over atwenty-four hour period in accordance with the present invention, thebottom portion of the graph showing a fan speed curve representingchanges in fan speed for a prior art variable speed fan drive system;

FIG. 10 is a side view, in elevation and partially in cross-section, ofan ACHE that utilizes the load bearing, direct drive fan system of thepresent invention;

FIG. 11A is a vibration bearing report, in graph form, resulting from atest of the load bearing permanent magnet motor and vibration sensingand analysis components of the present invention;

FIG. 11B is the same vibration bearing report of FIG. 11A, the vibrationbearing report showing a trip setting of 0.024G of a prior art gearbox;

FIG. 11C is a vibration severity graph showing the level of vibrationsgenerated by the load bearing permanent magnet motor of the presentinvention;

FIG. 12A is a side view, partially in cross-section, of the loadbearing, direct drive fan system of the present invention installed in acooling tower;

FIG. 12B is a bottom view of the load bearing permanent magnet motordepicted in FIG. 12A, the view showing the mounting holes in the loadbearing permanent magnet motor;

FIG. 13 shows an enlargement of a portion of the view shown in FIG. 12A;

FIG. 14 is a side view, in elevation, showing the interconnection of theload bearing permanent magnet motor shown in FIGS. 12A and 13 with a fanhub;

FIG. 15A is a diagram of a multi-cell cooling system that utilizes theload bearing, direct drive fan system of the present invention;

FIG. 15B is a top view of a multi-cell cooling system;

FIG. 15C is a block diagram of a motor-control center (MCC) that isshown in FIG. 15A;

FIG. 16A is a flowchart of a lock-out-tag-out (LOTO) procedure used tostop the fan in order to conduct maintenance procedures;

FIG. 16B is a flow chart a Flying-Start mode of operation that can beimplemented by the load bearing permanent magnet motor and variableprocess control system of the present invention;

FIG. 16C is a graph of speed versus time for the Flying-Start mode ofoperation;

FIG. 17 is a graph of an example of condenser performance as a functionof water flow rate (i.e. variable speed pumps and constant basintemperature);

FIG. 18 is a partial view of the load bearing permanent magnet motorshown in FIGS. 4 and 5A, the load bearing permanent magnet motor havingmounted thereto a line-replaceable vibration sensor unit in accordancewith another embodiment of the invention;

FIG. 19 is a partial view of the load bearing permanent magnet motorshown in FIGS. 4 and 5A, the load bearing permanent magnet motor havingmounted thereto a line replaceable vibration sensor unit in accordancewith a further embodiment of the invention;

FIG. 20 is partial view of the load bearing permanent magnet motor shownin FIGS. 4 and 5A having mounted thereto a line replaceable vibrationsensor unit in accordance with a further embodiment of the invention;

FIG. 21A is a top, diagrammatical view showing a fan-lock mechanism inaccordance with one embodiment of the invention, the fan lock mechanismbeing used on the rotatable shaft of the motor shown in FIGS. 4 and 5A,the view showing the fan lock mechanism engaged with the rotatable motorshaft in order to prevent rotation thereof;

FIG. 21B is a top, diagrammatical view showing the fan lock mechanism ofFIG. 21A, the view showing the fan lock mechanism disengaged from therotatable motor shaft in order to allow rotation thereof;

FIG. 21C is a side elevational view of the motor shown in FIGS. 4 and5A, the view showing the interior of the motor and the fan-lockmechanism of FIGS. 21A and 21B mounted on the motor about the upperportion of the motor shaft, the view also showing an additional fan-lockmechanism of FIGS. 21A and 21B mounted to the motor about the lowerportion of the motor shaft;

FIG. 22 is a side elevational view of the upper portion of the permanentmagnet motor of FIGS. 4 and 5A, the permanent magnet motor havingmounted thereto a caliper-type lock mechanism for engaging the upperportion of the shaft of the motor;

FIG. 23 is a side elevational view of the lower portion of the permanentmagnet motor of FIGS. 4 and 5A, the permanent magnet motor havingmounted thereto a caliper-type lock mechanism for engaging the lowerportion of the shaft of the motor;

FIG. 24 is a side elevational view of the lower portion of the permanentmagnet motor of FIGS. 4 and 5A, the permanent magnet motor havingmounted thereto a band-lock mechanism for engaging the lower portion ofthe shaft of the motor;

FIG. 25 is a side elevational view of the upper portion of the permanentmagnet motor of FIGS. 4 and 5A, the permanent magnet motor havingmounted thereto a band-lock mechanism for engaging the upper portion ofthe shaft of the motor;

FIG. 26 is a block diagram of the load bearing, direct drive fan systemand variable process control system of the present invention used with awet-cooling tower that is part of an industrial process;

FIG. 27 is a side view, in cross-section and in elevation, of a wetcooling tower that utilizes the load bearing, direct drive fan systemand variable process control system of the present invention, the loadbearing, direct drive motor being oriented such that the motor shaftextends downward;

FIG. 28 is a diagram of one type of hybrid cooling tower that utilizesthe load bearing, direct drive fan system and variable process controlsystem of the present invention;

FIG. 29 is a diagram of a commercial HVAC system that comprises adirect-drive air-handling system in accordance with one embodiment ofthe present invention;

FIG. 30A is a diagram of a commercial HVAC system in accordance withanother embodiment of the present invention;

FIG. 30B is a plan view of a wide chord fan utilized in the HVAC systemof FIG. 30A;

FIG. 31A is a side view of a centrifugal blower in accordance with oneembodiment of the present invention;

FIG. 31B is a view, partially in cross-section, of the interior of thecentrifugal blower of FIG. 31A;

FIG. 32 is a side view of a centrifugal blower in accordance withanother embodiment of the present invention, the view showing a motorand interior of the centrifugal blower;

FIG. 33 is a diagram of a commercial HVAC system in accordance withanother embodiment of the present invention;

FIG. 34 is a block diagram of a direct-drive air-handling system inaccordance with another embodiment of the present invention;

FIG. 35A is a diagram of a commercial HVAC system in accordance withanother embodiment of the present invention;

FIG. 35B is a plan view of the fan utilized in the HVAC system of FIG.35A; and

FIG. 36 is a diagram of a commercial HVAC system in accordance withanother embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

As used herein, the terms “cooling apparatus” or “cooling system” shallmean wet-cooling towers, forced draft air-cooled heat exchangers,induced draft air-cooled heat exchangers, mechanical cooling towers,hybrid cooling towers, hybrid heat exchangers and chillers. Examples ofwet-cooling towers are disclosed in U.S. Pat. No. 8,111,028, entitled“Integrated Fan Drive System For Cooling Tower” and U.S. Pat. No.4,955,585, entitled Hydraulically Driven Fan System For Water CoolingTower”. The entire disclosure of U.S. Pat. No. 8,111,028 is herebyincorporated by reference. Examples of forced-draft and induced draftair-cooled heat exchangers are disclosed in U.S. Pat. No. 8,188,698,entitled “Integrated Fan Drive System For Air-Cooled Heat Exchanger(ACHE)”. The entire disclosure of U.S. Pat. No. 8,188,698 is herebyincorporated by reference. An example of a hybrid heat exchangerapparatus is disclosed in US Patent Application Publication No.US20120067546, entitled “Hybrid Heat Exchanger Apparatus And Method OfOperating The Same”. An example of a hybrid cooling tower is disclosedin European Patent Application Publication No. EP0968397, entitled“Hybrid Cooling Tower”.

As used herein, the term “fan loads” shall include fan dead weight, fanforward thrust, fan reverse thrust, yaw loads, torque reaction loads,fan forces and moments.

As used herein, the term “motor” shall mean any electric motor with arotor and stator that creates flux.

As used herein, the terms “motor casing” or “motor housing” are usedinterchangeably and shall have the same meaning and include motorcasings or housings of stacked lamination frame configuration.

As used herein, the term “load bearing, direct drive system” shall meana drive system that comprises a load bearing, direct drive motor thathas its shaft directly coupled to a cooling tower fan wherein the loadbearing, direct drive motor provides the required torque and speed rangefor rotating the fan while simultaneously supporting the fan loads andmaintaining the required gap between the rotor and stator in order tocreate flux.

As used herein, the terms “process”, “plant process” or “industrialprocess” shall mean an industrial process such as a petroleum refinery,power plant, turbine, crude cracker, fertilizer plant, glassmanufacturing plant, chemical plant, etc.

As used herein, the terms “process liquid” means the liquids, such aswater or other coolant, that are used for cooling purposes in theprocess.

As used herein, the terms “process demand” or “process cooling demand”mean the amount of cooling liquids used by the process.

As used herein, the term “part-plant load” means process demand that isless than maximum process demand.

As used herein, the terms “basin temperature” or “collection basintemperature” mean the temperature of the water or other liquid that isin the collection basin of a wet-cooling tower;

As used herein, the term “Environmental Stress” shall mean,collectively, ambient temperature, relative humidity, dry-bulbtemperature, wet-bulb temperature, wind speed, wind direction, solargain and barometric pressure.

As used herein, the term “Cooling Tower Thermal Capacity” is theheat-rejection capability of the cooling tower. It is the amount of coldwater that can be returned to the process for given temperature and flowrate at maximum hot-day and wet-bulb conditions. Cooling Tower ThermalCapacity will be reduced as the cooling tower components degrade, suchas the fill material becoming clogged due to poor water quality. For agiven ΔT (difference between temperatures of hot and cold water) and theflow rate, the cooling tower fans will have to operate at higher speedand for longer amounts of time given the environmental stress in adegraded tower (that is being monitored and trended).

As used herein, the term “process thermal demand” or “thermal demand”means the heat that has to be removed from the process liquid (e.g.water) by the cooling tower. In its simplest terms, thermal demand ofthe process is expressed as the water temperature from the process (hotwater) and water temperature returned to the process (cold water) for agive flow rate;

As used herein, the terms “fan map” and “fan performance curve”represent the data provided for fan blades with a given solidity.Specifically, the data represents the airflow of air moved by a specificfan diameter, model and solidity for a given fan speed and pitch at agiven temperature and wet-bulb (air density).

As used herein, the terms “trending” or “trend” means the collection ofcooling tower parameters, events and calculated values with respect totime that define operating characteristics such as cooling performanceas a function of environmental stress and Process Thermal Demand.

Referring to FIGS. 2 and 4, there is shown the variable process controlsystem of the present invention for managing the operation of fans andpumps in cooling apparatus 10. As stated in the foregoing description,cooling apparatus 10 may be any one of a variety of cooling apparatusesor cooling systems including a wet-cooling tower, hybrid cooling tower,mechanical tower, forced draft air-cooled heat exchanger, induced draftair-cooled heat exchanger (ACHE), hybrid heat exchanger, chiller andHVAC system. All of these cooling apparatuses and cooling systems arecommonly used to cool liquids used in a process such as an industrialprocess. Examples of applicable industrial processes include petroleumrefineries, chemical plants, etc. For purposes of describing the aspectsand embodiments of the present invention, cooling apparatus 10 isdescribed herein as a wet-cooling tower. Cooling apparatus 10 comprisesfan 12 and fan stack 14. As is known in the field, cooling towers mayutilize fill material which is described in the aforementioned U.S. Pat.No. 8,111,028. Fan 12 comprises hub 16 and a plurality of fan blades 18that are connected to and extend from hub 16. The system of the presentinvention comprises a high-torque, variable speed, load bearing electricmotor 20. For purposes of describing the invention, the ensuingdescription is in terms of motor 20 being a load bearing permanentmagnet motor. However, it is to be understood that motor 20 can beconfigured as any other high-torque, variable speed, load bearingelectric motor, some of which are described in the ensuing description.Motor 20 comprises motor housing or casing 21A (see FIG. 4). Casingcomprises top cover 21A and bottom cover 21B. Motor 20 further comprisesrotatable shaft 24. In this embodiment, motor shaft 24 is directlyconnected to fan hub 16. The connection of motor shaft 24 to fan hub 16is described in detail in the ensuing description. It is to be thatmotor 20 can interfaces with all fans having diameters between about onefoot and forty feet. Motor shaft 24 can be directly connected to thefan, or directly connected to the fan hub, or connected to the fan witha shaft adapter, or connected to the fan hub with a shaft adapter, orconnected to the fan with a shaft extension.

Referring to FIG. 2, power cable 105 has one end that is terminated atmotor 20. Specifically, power cable 105 is factory sealed to Class One,Division Two, Groups B, C and D specifications and extends through themotor housing 21 and is terminated within the interior of motor housing21 during the assembly of motor 20. Therefore, when installing motor 20in a cooling apparatus, it is not necessary for technicians or otherpersonnel to electrically connect power cable 105 to motor 20. The otherend of power cable 105 is electrically connected to motor disconnectjunction box 106. Power cable 105 is configured as an area classified,VFD rated and shielded power cable. Motor disconnect junction box 106includes a manual emergency shut-off switch. Motor disconnect junctionbox 106 is primarily for electrical isolation. Power cable 105 comprisesthree wires that are electrically connected to the shut-off switch inmotor-disconnect junction box 106. Power cable 107 is connected betweenthe shut-off switch in motor-disconnect junction box 106 and VFD device22. Power cable 107 is configured as an area classified, VFD rated andshielded power cable. The electrical power signals generated by VFDdevice 22 are carried by power cable 107 which delivers these electricalpower signals to junction box 106. Motor power cable 105 is connected topower cable 107 at junction box 106. Thus, motor power cable 105 thenprovides the electrical power signals to motor 20.

Referring to FIGS. 2 and 4, quick-disconnect adapter 108 is connected tomotor housing 21. In one embodiment, quick-disconnect adapter 108 is aTurck Multifast Right Angle Stainless Connector with Lokfast Guard,manufactured by Turck Inc. of Minneapolis, Minn. The sensors internal tomotor housing 21 are wired to quick-disconnect adapter 108. Cable 110 isconnected to quick-disconnect adapter 108 and to communication datajunction box 111. Communication data junction box 111 is located on thefan deck. The electronic components in communication data junction box111 are powered by a voltage source (not shown). Cable 110 is configuredas an area-classified multiple connector shielded flexible controlcable. Cable 112 is electrically connected between communication datajunction box 111 and data acquisition device 200 (referred to herein as“DAQ device 200”). In one embodiment, cable 112 is configured as anEthernet cable. As described in the foregoing description, VFD device 22is in data communication with Data Acquisition Device (DAQ) device 200.VFD device 22 and DAQ device 200 are mounted within Motor CenterEnclosure 26 (see FIGS. 2 and 4). A Motor Control Enclosure typically isused for a single motor or fan cell. The MCE 26 is typically located onthe fan deck in close proximity to the motor. The MCE 26 houses VFDdevice 22, DAQ device 200, industrial computer 300 and the powerelectronics. In one embodiment, MCE 26 is a NEMA 4× Rated Cabinet. VFDdevice 22 and DAQ device 200 are discussed in detail in the ensuingdescription.

Referring to FIGS. 4 and 5A, the load bearing, direct drive fan systemof the present invention comprises high torque, low variable speed, loadbearing motor 20. The casing, bearings and shaft design of motor 20ensures structural and dynamic integrity and also provides for ventingand cooling of motor 20 without the use of a shroud or similar devicetypically used in prior art fan drive systems. Motor 20 comprises abearing system and structure that supports the fan loads of largediameter fans, e.g. rotational loads, axial thrust loads, axial reversethrust loads, fan dead weight, radial loads, moment loads, and yawloads. Thus, motor 20 can bear the loads of a cooling tower fan whetherthe fan is rotating or at 0.0 RPM. Motor 20 can be mounted in anyposition such that output shaft 24 can be oriented in any position, e.g.upward, downward, horizontal, angulated, etc. This can be achievedbecause motor 20 is a sealed motor and eliminates the oil bath systemwhich is used in prior art systems. In this embodiment, motor 20 is apermanent magnet motor. Shaft 24 of motor 20 is directly connected tothe fan hub 16. Thus, motor 20 directly drives fan 12 without the losscharacteristics and mechanical problems typical of prior art gearboxdrive systems. Motor 20 has a relatively high flux density and iscontrolled only by electrical signals provided by VFD device 22. Thus,there are no drive shaft, couplings, gear boxes or related componentswhich are found in the prior art gearbox-type fan drive systems. Motor20 comprises stator 32, rotor 34 and spherical roller thrust bearing 40that is located at the lower end of motor shaft 24. Referring to FIG.5A, in accordance with one embodiment of the invention, the clearancebetween stator 32 and rotor 34 is 0.060 inch and is designated by theletter “X” in FIG. 5A. Spherical roller thrust bearing 40 absorbs thethrust load caused by the weight of fan 12 and fan thrust forces due toairflow. Motor 20 further comprises cylindrical roller bearing 42 thatis located immediately above spherical roller thrust bearing 40.Cylindrical roller bearing 42 opposes radial loads at the thrust end ofshaft 24. Radial loads are caused by fan assembly unbalance and yawmoments due to unsteady wind loads. Motor 20 further comprises taperedroller output bearing 44. Tapered roller output bearing 44 is configuredto have a high radial load capability coupled with thrust capability tooppose the relatively low reverse thrust loads that occur duringde-icing (reverse rotation) or high wind gust. Although three bearingsare described, motor 20 is actually a two-bearing system. The “twobearings” are cylindrical roller bearing 42 and tapered roller outputbearing 44 because these two bearings are radial bearings that locateand support the shaft relative to motor casing housing 21 and themounting structure. Spherical roller thrust bearing 40 is a thrustbearing that is specifically designed so that it does not provide anyradial locating forces but only axial location. In this embodiment, theparticular design, structure and location of the bearings and theparticular design and structure of the motor casing 21, rotor 34 andshaft 24 cooperate to maintain the clearance “X” of 0.060 inch betweenstator 32 and rotor 34. It is necessary to maintain this clearance “X”of 0.060 inch in order to produce the required electrical flux densityand obtain optimal motor operation. Thus, in accordance with theinvention, the bearings of the motor bear the loads of a rotating fanwhile simultaneously maintaining the clearance “X” of 0.060 inch betweenstator 32 and rotor 34. This feature is unique to motor design and isreferred to herein as a “load bearing motor”. It is to be understoodthat, depending upon the application, the sizes and dimensions of themotor casing, stator, rotor, shaft and bearing system may vary such thatthe clearance “X” is different than 0.060 inch. The design of permanentmagnet motor 20 has a reduced Life-Cycle Cost (LCC) as compared to theprior art gearbox fan drive systems described in the foregoingdescription. Bearing housing 50 houses bearing 44. Bearing housing 52houses bearings 40 and 42. Bearing housings 50 and 52 are isolated fromthe interior of motor housing 21 by nitrile rubber, double lip-styleradial seals. The combination of the low surface speed of motor shaft 24and synthetic lubricants result in accurate predicted seal reliabilityand operational life. The permanent magnet motor 20 includes sealhousing 53 that comprises a Grounded Inpro™ Seal bearing isolator. ThisGrounded Inpro Seal™ bearing isolator electrically grounds the bearingsfrom the VFD. The motor shaft seal comprises an Inpro™ seal bearingisolator in tandem with a double radial lip seal. The Inpro™ sealbearing isolator is mounted immediately outboard of the double radiallip seal. The function of the Inpro™ seal is to seal the area whereshaft 24 penetrates top cover 21A of motor housing 21. The Inpro sealalso incorporates a fiber grounding brush to prevent impressed currentsin shaft 24 that could damage the bearings. The double radial lip sealexcludes moisture and solid contaminants from the seal lip contact.Motor housing 21 includes bottom cover 21B. Motor 20 is a sealed systemunlike typical prior art gearbox systems which have an open lubricationdesign. Such prior art gearbox systems are not suited for cooling towerservice since the open lubrication system becomes contaminated from thechemicals, humidity and biological contamination in the cooling tower.The design and structure of motor 20 eliminates these problems of priorart gearbox systems. Since motor 20 is sealed, motor 20 may be operatedin wet or dry environments and in any orientation, e.g. motor shaft inupward vertical orientation, motor shaft in downward verticalorientation or motor shaft oriented at an angle. In one embodiment,permanent magnet motor 20 has the following operational and performancecharacteristics:

-   -   Speed Range: 0-250 RPM    -   Maximum Power: 133 hp/100 KW    -   Number of Poles: 16    -   Motor Service Factor: 1:1    -   Rated Current: 62 A (rms)    -   Peak Current: 95 A    -   Rated Voltage: 600 V    -   Drive Inputs: 460 V, 3 phase, 60 Hz, 95A (rms max. continuous)    -   Area Classification: Class 1, Division 2, Groups B, C, D    -   Insulation Class H

Permanent magnet motor 20 can be configured to have differentoperational characteristics. For example, permanent magnet motor 20 canbe configured to have a maximum rotational speed less than or equal to900 RPM. However, it is to be understood that in all embodiments, motor20 is designed to the requirements of Class 1, Div. 2, Groups B, C andD. FIG. 6 shows a plot of speed vs. horsepower for motor 20. However, itis to be understood that the aforesaid operational and performancecharacteristics just pertain to one embodiment of permanent magnet motor20 and that motor 20 may be modified to provide other operational andperformance characteristics that are suited to a particular application.Referring to FIG. 7, there is shown a graph that shows “Efficiency %”versus “Motor Speed (RPM)” for motor 20 and a prior art fan drive systemusing a prior art, variable speed, induction motor. Curve 100 pertainsto motor 20 and curve 102 pertains to the prior art fan drive system. Ascan be seen in the graph, the efficiency of motor 20 is relativelyhigher than the prior art fan drive system for motor speeds betweenabout 60 RPM and about 200 RPM. The characteristics of permanent magnetmotor 20 of the present invention provide the flexibility of optimizingfan pitch for a given process demand.

Motor 20 has relatively low maintenance with a five year lube interval.The design and architecture of motor 20 substantially reduces theman-hours associated with service and maintenance that would normally berequired with a prior art, induction motor fan drive system. The bearingL10 life is calculated to be 875,000 hours. In some instances, motor 20can eliminate up to 1000 man-hours of annual service and maintenance ina cooling tower.

In an alternate embodiment, motor 20 is configured with auto-lube greaseoptions as well as grease fittings depending on the user. Motor 20eliminates shaft, coupling and related drive-train vibrations, torsionalresonance and other limitations typically found in prior art drivesystems and also eliminates the need for sprag-type clutches typicallyused to prevent opposite rotation of the fans. Motor 20 eliminateswidely varying fan-motor power consumption problems associated withprior art gearboxes due to frictional losses caused by mechanicalcondition, wear and tear, and impact of weather on oil viscosity andother mechanical components. The high, constant torque of motor 20produces the required fan torque to accelerate the fan through the speedrange.

Referring to FIGS. 2, 4 and 5A, shaft 24 of permanent magnet motor 20rotates when the appropriate electrical signals are applied to permanentmagnet motor 20. Rotation of shaft 24 causes rotation of fan 12. VFDdevice 22 comprises a plurality of independently controlled programmablevariable frequency drive (VFD) devices 23A, 23B, 23C, 23D and 23E (seeFIG. 26). VFD device 23A controls motor 20. The remaining VFD devicescontrol the permanent magnet motors in the variable speed pumps (seeFIG. 26). DAQ device 200 provides control signals to each of the VFDdevices 23A, 23B, 23C, 23D and 23E. These features are discussed laterin the ensuing description. VFD device 23A provides the appropriateelectrical power signals to motor 20 via cables 107 and 105. There istwo-way data communication between VFD device 22 and DAQ device 200. DAQdevice 200 comprises a controller module which comprises a computerand/or microprocessor having computer processing capabilities,electronic circuitry to receive and issue electronic signals and abuilt-in keyboard or keypad to allow an operator to input commands. Inone embodiment, DAQ device 200 comprises a commercially available CSESemaphore TBox RTU System that comprises a data acquisition system,computer processors, communication modules, power supplies and remotewireless modules. The CSE Semaphore TBox RTU System is manufactured byCSE Semaphore, Inc. of Lake Mary, Fla. In a preferred embodiment, theCSE Semaphore TBox RTU System is programmed with a commerciallyavailable computer software packages known as Dream Report™ and TView™which analyze collected data. In an alternate embodiment, the CSESemaphore TBox RTU System is programmed with commercially availablesoftware known as TwinSoft™. In DAQ device 200 is described in detail inthe ensuing description. VFD device 22 comprises a variable frequencycontroller 120 and signal interface 122. VFD device 22 controls thespeed and direction (i.e. clockwise or counterclockwise) of permanentmagnet motor 20. AC voltage signals are inputted into variable frequencycontroller 120 via input 124. Variable frequency controller 120 outputsthe power signals that are inputted into motor 20 via power cables 107and 105. Referring to FIG. 4, signal interface 122 is in electricalsignal communication with DAQ device 200 via data signal bus 202 andreceives signals to start, reverse, accelerate, decelerate, coast, stopand hold motor 20 or to increase or decrease the RPM of motor 20. In apreferred embodiment, signal interface 122 includes a microprocessor.Signal interface 122 outputs motor status signals over data bus 202 forinput into DAQ device 200. These motor status signals represent themotor speed (RPM), motor current (ampere) draw, motor voltage, motorpower dissipation, motor power factor, and motor torque.

VFD device 23A measures motor current, motor voltage and the motor powerfactor which are used to calculate energy consumption. VFD device 23Aalso measures motor speed, motor power and motor torque. VFD device 23Aalso measures Run Time/Hour Meter in order to provide a time stamp andtime-duration value. The time stamp and time-duration are used byindustrial computer 300 for failure and life analysis, FFT processing,trending, and predicting service maintenance. Industrial computer 300 isdiscussed in detail in the ensuing description.

Referring to FIGS. 4 and 26, VFD devices 23B, 23C, 23D and 23E outputselectrical power signals 1724, 1732, 1740 and 1754, respectively, forcontrolling the variable speed pumps 1722, 1730, 1738 and 1752,respectively, that pump liquid (e.g. water) to and from the coolingtower. This aspect of the present invention is discussed in detail inthe ensuing description.

In one embodiment, each of the VFD devices is configured as anABB-ACS800 VFD manufactured by ABB, Inc.

Referring to FIG. 8, there is shown a partial view of a coolingapparatus 10 that utilizes the direct drive fan system of the presentinvention. In this embodiment, cooling apparatus 10 comprises awet-cooling tower and motor 20 is the load bearing permanent magnetmotor discussed in the foregoing description. The wet-cooling towercomprises fan 12, fan stack 14, fan hub 16, and fan blades 18, all ofwhich were discussed in the foregoing description. Fan stack 14 issupported by fan deck 250. Fan stack 14 can be configured to have aparabolic shape or a cylindrical (straight) shape as is well known inthe field. Motor 20 is supported by a metal frame or ladder frame ortorque tube that spans across a central opening (not shown) in fan deck250. Motor shaft 24 is configured as a keyed shaft and is directlyconnected to fan hub 16 (see FIG. 14). Power cables 105 and 107,motor-disconnect junction box 106 and quick-disconnect connector 108were previously discussed in the foregoing description. Power cable 107is connected between motor-disconnect junction box 106 and variablefrequency controller 120 of VFD device 22 (see FIGS. 2 and 4) which islocated inside MCE 26. Referring to FIGS. 2, 4 and 8, cable 110 iselectrically connected between quick-disconnect adapter 108 andcommunication data junction box 111. These signals are fed to the DAQdevice 200 located in MCE 26 via cable 112 as described in the foregoingdescription. Industrial computer 300 is also located within MCE 26.

Referring to FIG. 10, there is shown an air-cooled heat exchanger (ACHE)that utilizes the direct drive fan system of the present invention. Thisparticular ACHE is an induced-draft ACHE. The remaining portion of theACHE is not shown since the structure of an ACHE is known in the art.The ACHE comprises tube bundle 800, vertical support columns 801A and801B, parabolic fan stack 802, horizontal support structure 804, supportmembers 805 and fan assembly 12. Fan assembly 12 comprises fan hub 16and fan blades 18 that are attached to fan hub 16. Vertical shaft 806 isconnected to fan hub 16 and coupled to motor shaft 24 with coupling 808.Motor 20 is connected to and supported by horizontal member 804.Additional structural supports 810A and 810B add further stability tomotor 20. Coupling 808 drives a pair of separate bearing systems 850 and852. The separate bearing systems 850 and 852 allow the ACHE supportstructure to bear either full or partial fan loads.

As described in the foregoing description, one end of power cable 105 isterminated at motor 20 and the other end of power cable 105 iselectrically connected to the motor disconnect junction box 106. Powercable 107 is connected between motor disconnect junction box 106 and VFDdevice 22. As described in the foregoing description, cable 110 iselectrically connected between quick-disconnect adapter 108 andcommunication data junction box 111, and cable 112 is electricallyconnected between communication data junction box 111 and DAQ device200. VFD device 22 and DAQ device 200 are mounted within a Motor ControlEnclosure (MCE) which is not shown in FIG. 10 but which was described inthe foregoing description.

Referring to FIG. 2, the system of the present invention furthercomprises industrial computer 300. Industrial computer 300 is alwaysco-located with DAQ device 200. Industrial computer 300 is in datacommunication with data bus 302. Data bus 302 is in data communicationwith DAQ device 200. Industrial computer 300 is responsible forpost-processing of performance data of the cooling tower and the systemof the present invention. Included in this post-processing function aredata logging and data reduction. Industrial computer 300 is programmedwith software programs, an FFT algorithm and other algorithms forprocessing system performance data, environmental data and historicaldata to generate performance data reports, trend data and generatehistorical reports based on performance data it receives from DAQ device200. Industrial computer 300 also stores data inputted by the operatorsthrough the plant DCS 315. Such stored data includes fan maps, fanpitch, Cooling Tower Design Curves, and Thermal Gradient analysis data.The wet-bulb temperature data is continually calculated from relativehumidity and ambient temperature and is inputted into industrialcomputer 300. User input 304 (e.g. keyboard) 304 and display 306 (e.g.display screen) are in data signal communication with industrialcomputer 300. An operator uses user input 304 to input commands intoindustrial computer 300 to generate specific types of processed data.Industrial computer 300 displays on display 306 real-time data relatingto the operation of the cooling tower and the system of the presentinvention, including motor 20. Industrial computer 300 is also used toprogram new or revised data into DAQ device 200 in response to changingconditions such as variable process demand, motor status, fan condition,including fan pitch and balance, and sensor output signals. The sensoroutput signals are described in the ensuing description. In a preferredembodiment, industrial computer 300 is in data signal communication withhost server 310. Host service 310 is in data signal communication withone or more remote computers 312 that are located at remote locations inorder to provide off-site monitoring and analysis. Industrial computer300 is also in data signal communication with the plant DistributedControl System (DCS) 315, shown in phantom in FIGS. 2 and 3. Users oroperators can input data into DCS 315 including revised temperatureset-points, or revised pump flow rates or even change the plant loadsetting from full plant load to part-plant load. This revisedinformation is communicated to industrial computer 300 which then routesthe information to DAQ device 200. DAQ device 200 and industrialcomputer 300 provide real-time cooling performance monitoring, real-timecondition fault monitoring and autonomous control of fan speed.

In a preferred embodiment, industrial computer 300 receives continuousweather data from the national weather surface or NOAA. Industrialcomputer 300 can receive this data directly via an Internet connectionor it can receive the data via host server 310. Industrial computer 300converts such weather data to a data form that can be processed by DAQdevice 200. In a preferred embodiment, as shown in FIG. 2, the variableprocess control system of the present invention further compriseson-site weather station 316 which is in data signal communication withthe Internet and DAQ device 200. On-site weather station 316 comprisescomponents and systems to measure parameters such as wind speed anddirection, relative humidity, ambient temperature, barometric pressureand wet-bulb temperature. These measured parameters are used byindustrial computer 300 to determine Cooling Tower Thermal Capacity andalso to determine the degree of icing on the tower. These measureparameters are also used for analysis of the operation of the coolingtower. On-site weather station 316 also monitor's weather forecasts andissues alerts such as high winds, freezing rain, etc.

In one embodiment, the VFD device 22, DAQ device 200, industrialcomputer 300 and power electronics are located in MCE 26. TheDistributed Control System (DCS) 315 is integrated with industrialcomputer 300 at MCE 26. Operators would be able to log onto industrialcomputer 300 for trending information and alerts. DAQ device 200automatically generates and issues alerts via email messages or SMS textmessages to multiple recipients, including the Distributed ControlSystem (DCS), with attached documents and reports with live andhistorical information as well as alarms and events.

In one embodiment, industrial computer 300 is programmed to allow anoperator to shut down or activate the direct drive fan system from aremote location.

Referring to FIGS. 2 and 4, VFD device 22 controls the speed, directionand torque of fan 12. DAQ device 200 is in electrical signalcommunication with VFD device 22 and provides signals to the VFD device22 which, in response, outputs electrical power signals to motor 20 inaccordance with a desired speed, torque and direction. Specifically, theDAQ device 200 generates control signals for VFD device 22 that definethe desired fan speed (RPM), direction and torque of motor 20. DAQdevice 200 is also programmed to issue signals to the VFD device 22 tooperate the fan 12 in a normal mode of operation referred to herein as“energy optimization mode”. This “energy optimization mode” is describedin detail in the ensuing description. When acceleration of motor 20 isdesired, DAC device 200 outputs signals to VFD device 22 that define aprogrammed rate of acceleration. Similarly, when deceleration of motor20 is desired, DAQ device 200 outputs signals to VFD device 22 thatdefine a programmed rate of deceleration. If it is desired to quicklydecrease the RPM of motor 20, DAQ device 200 outputs signals to VFDdevice 22 that define a particular rate of deceleration that continuesuntil the motor comes to a complete stop (e.g. 0.0 RPM).

DAQ device 200 provides several functions in the system of the presentinvention. DAQ device 200 receives electronic data signals from allsensors and variable speed pumps (discussed in the ensuing description).DAQ device 200 also continuously monitors sensor signals sent to theaforesaid sensors to verify that these sensors are working properly. DAQdevice 200 is programmed to issue an alert is there is a lost sensorsignal or a bad sensor signal. DAQ device 200 automatically adjusts theRPM of motor 20 in response to the sensor output signals. Accordingly,the system of the present invention employs a feedback loop tocontinuously adjust the RPM of motor 20, and hence fan 12, in responseto changes in the performance of the fan, cooling tower characteristics,process load, thermal load, pump flow-rate and weather and environmentalconditions. A diagram of the feedback loop is shown in FIG. 3. DAQdevice 200 is programmable and can be programmed with data defining orrepresenting the tower characteristics, trend data, the geographicallocation of the cooling tower, weather and environmental conditions. DAQdevice 200 is configured with internet compatibility (TCP/IPcompatibility) and automatically generates and issues email messages orSMS text messages to multiple recipients, including the DistributedControl System (DCS), with attached documents and reports with live andhistorical information as well as alarms and events. In a preferredembodiment, DAQ device 200 comprises multiple physical interfacesincluding Ethernet, RS-232, RS-485, fiber optics, Modbus, GSM/GPRS, PSTNmodem, private line modem and radio. Preferably, DAQ device 200 hasSCADA compatibility. In one embodiment, DAQ device 200 is configured asa commercially available data acquisition system. In an alternateembodiment, DAQ device 200 is configured to transmit data to industrialcomputer 300 via telemetry signals.

Referring again to FIG. 3, the feedback loops enable continuousmonitoring of the operation of motor 20, fan 12 and the variable speedpumps and also effect automatic adjustment of the RPM of motor 20 and ofthe permanent magnet motors in the variable speed pumps (see FIG. 26).The feedback loops shown in FIG. 3 allows motor 20 to be operated in anyone of a plurality of modes of operation which are discussed in theensuing description.

Flying Start Mode

The variable process control system of the present invention isconfigured to operate in a “Flying Start Mode” of operation withinfinite control of fan 12. A flow chart of this mode of operation isshown in FIG. 16B. In this mode of operation, VFD device 22 senses thedirection of the fan 12 (i.e. clockwise or counter-clockwise) and then:(a) applies the appropriate signal to motor 20 in order to slow fan 12to a stop (if rotating in reverse), or (b) ramps motor 20 to speed, or(c) catches fan 12 operating in the correct direction and ramps tospeed. The graph in FIG. 16C illustrates the “Flying Start Mode”. Thenomenclature in FIG. 16C is defined as follows:

“A” is a desired, fixed or constant speed for motor 20 (i.e. constantRPM);

“B” is the Time in seconds for VFD device 22 to bring motor 20 from 0.0RPM to desired RPM (i.e. Ramp-Up Time).

“C” is the Time in seconds for VFD device 22 to bring motor 20 fromdesired RPM to 0.0 RPM (i.e. Ramp-Down Time).

“Angle D” is the acceleration time in RPM/second and is defined as“cos(A/B)”;

“Angle E” is the deceleration time in RPM/second and is defined as“cos(A/C)”;

Angle D and Angle E may be identical, but they do not have to be.

The “Flying Start” mode may be implemented if any of the followingconditions exist:

Condition #2: Motor 20 is detected at 0.0 RPM. The VFD device 22accelerates motor 20 to desired RPM in “B” seconds.

Condition #1: Motor 20 is detected running in reverse direction. The VFDdevice 22 calculates time to bring motor 20 to 0.0 RPM at rate of D.Motor 20 is then accelerated to “A” RPM. Total time for motor to reach“A” RPM is greater than “B” seconds.

Condition #3: Motor 20 is detected running in forward direction. VFDdevice 22 calculates position of motor 20 on ramp and uses rate “D” toaccelerate motor to “A” RPM. Total time for motor 20 to reach “A” RPM isless than “B” seconds.

Condition #4—Motor is detected running greater than “A” RPM. VFD device22 calculates time to decelerate motor to “A” RPM using rate E.

This Flying Start mode of operation is possible because the novelbearing design of motor 20 allows the fan to windmill in reverse.

Soft Start Mode

The variable process control system of the present invention isconfigured to operate in a “Soft Start Mode” of operation. In this modeof operation, with VFD device 22 is programmed to initiate accelerationin accordance with predetermined ramp rate. Such a controlled rate ofacceleration eliminates breakage of system components with “across theline starts”. Such “breakage” is common with prior art gearbox fan drivesystems.

Hot Day Mode

Another mode of operation that can be implemented by the variableprocess control system of the present invention is the “hot day” mode ofoperation. The “hot day” mode of operation is used when more cooling isrequired and the speed of all fans is increased to 100% maximum fan tipspeed. The “hot day” mode of operation can also be used in the event ofan emergency in order to stabilize an industrial process that mayrequire more cooling.

Energy Optimization Mode

The variable process control system of the present invention isconfigured to operate in an “Energy Optimization Mode”. In this mode ofoperation, the fan 12 and the variable speed pumps 1722, 1730, 1738, and1752 (see FIG. 26) are operated to maintain a constant basintemperature. The control of fan speed is based upon the cooling towerdesign, predicted and actual process demand and historical environmentalconditions with corrections for current process and environmentalconditions. Industrial computer 300 uses historical data to predict theprocess demand for a current day based on historical process demandpatterns and historical environmental conditions, and then calculates afan speed curve as a function of time. The calculated fan speed curverepresents the minimal energy required to operate the fan throughout thevariable speed range for that current day in order to meet the constantbasin temperature demand required by the industrial process. In realtime, the variable process control system processes the actualenvironmental conditions and industrial process demand and providespredictions and corrections that are used to adjust the previouslycalculated fan speed curve as a function of time. VFD device 22 outputselectrical power signals in accordance with the corrected fan speedcurve. The system utilizes logic based on current weather forecasts,from on-site weather station 316, as well as historical trendspertaining to past operating data, past process demand, and pastenvironmental conditions (e.g. weather data, temperature and wet-bulbtemperature) to calculate the operating fan speed curve. In this EnergyOptimization Mode, the fan operation follows the changes in the dailywet-bulb temperature. Fan operation is represented by a sine wave over a24 hour period, as shown in the top portion of the graph in FIG. 9,wherein the fan speed transitions are smooth and deliberate and follow atrend of acceleration and deceleration. In FIG. 9, the “Y” axis is“Motor Speed” and the “X” axis is “Time”. The fan speed curve in the topportion of the graph in FIG. 9 (Energy Optimization Mode” is directlyrelated to wet-bulb temperature. The duration of time represented by the“X” axis is a twenty-four period. The variable process control system ofthe present invention uses a Runge-Kutter algorithm that analyzeshistorical process demand and environmental stress as well as currentprocess demand and environmental stress to generate a fan speed curvethat results in energy savings. This control of the fan speed istherefore predictive in nature so as to optimize energy consumption asopposed to being reactive to past data. Such a process minimizes theenergy consumed in varying the fan speed. Such smooth fan speedtransitions of the present invention are totally contrary to the abruptfan speed transitions of the prior art fan drive systems, which areillustrated at the bottom of the graph in FIG. 9. The fan speedtransitions of the prior art fan drive system consist of numerous,abrupt fan-speed changes occurring over a twenty-four period in shortspurts. Such abrupt fan speed changes are the result of the prior artvariable speed logic which is constantly “switching” or accelerating anddecelerating the fan to satisfy the basin temperature set point.

Therefore, the Energy Optimization Mode of the present invention usesthe cooling tower data, process demand, geographical location data,current environmental data and historical trends to predict fan speedaccording to loading so as to provide a smooth fan-speed curvethroughout the day. Such operation minimizes the fan speed differentialand results in optimized energy efficiency.

Soft-Stop Mode

The variable process control system and motor 20 of the presentinvention are configured to operate in a “Soft-Stop Mode” of operation.In this mode of operation, DAQ device 200 provides signals to VFD device22 to cause VFD device 22 to decelerate motor 20 under power RPM inaccordance with a predetermined negative ramp rate to achieve acontrolled stop. This mode of operation also eliminates breakage ofand/or damage to system components. This “Soft-Stop Mode” quickly bringsthe fan to a complete stop thereby reducing damage to the fan. Theparticular architecture of motor 20 allows the fan to be held at zeroRPM to prevent the fan from windmilling in reverse. Such a featureprevents the fan from damaging itself or damaging other componentsduring high winds and hurricanes. Such a “Soft Stop Mode” of operationis not found in prior art fan drive systems using induction motors.

Fan Hold Mode

The variable process control system and motor 20 of the presentinvention are configured to operate in a “Fan-Hold Mode”. This mode ofoperation is used during a lock-out, tag-out (LOTO) procedure which isdiscussed in detail in the ensuing description. “If a LOTO procedure isto be implemented, then motor 20 is first brought to 0.00 RPM using the“Soft-Stop Mode”, then the “Fan-Hold Mode” is implemented in order toprevent the fan from windmilling. Fan-hold is a function of the designof permanent magnet motor 20. DAQ device 200 provides signals to VFDdevice 22 to cause VFD device 22 to decelerate motor 20 under power at apredetermined negative ramp rate to achieve a controlled stop of fan 12in accordance with the “Soft-Stop Mode”. VFD device 22 controls motor 20under power so that fan 12 is held stationary. Next, the motor shaft 24is locked with a locking mechanism (as will be described in the ensuingdescription). Then, all forms of energy (e.g. electrical power) areremoved according to the Lock-Out-Tag-Out (LOTO) procedure and then fan12 can be secured. In prior art drive systems using prior art inductionmotors, attempting to brake and hold a fan would actually cause damageto the induction motor. However, such problems are eliminated with the“Soft-Stop and “Fan-Hold Modes”.

The variable process control system and motor 20 of the presentinvention can also implement a “Reverse Operation Mode”. In this mode ofoperation, motor 20 is operated in reverse. This mode of operation ispossible since there are no restrictions or limitations on motor 20unlike prior art gearbox fan drive systems which have many limitations(e.g. lubrication limitations). The unique bearing system of motor 20allows unlimited reverse rotation of motor 20. Specifically, the uniquedesign of motor 20 allows design torque and speed in both directions.

Reverse Flying Start Mode

The variable process control system and motor 20 of the presentinvention can also implement a “Reverse Flying-Start Mode” of operation.In this mode of operation, the Flying Start mode of operation isimplemented to obtain reverse rotation. The motor 20 is firstdecelerated under power until 0.00 RPM is attained than then reverserotation is immediately initiated. This mode of operation is possiblesince there are no restrictions or limitations on motor 20 in reverse.This mode of operation is useful for de-icing.

Lock-Out Tag Out

In accordance with the invention, a particular Lock-Out Tag-Out (LOTO)procedure is used to stop fan 12 in order to conduct maintenance on fan12. A flow-chart of this procedure is shown in FIG. 16. Initially, themotor 20 is running at the requested speed. In one embodiment, in orderto initiate the LOTO procedure, an operator uses the built-in keypad ofDAQ device 200 to implement “Soft-Stop Mode” so as to cause motor 20,and thus fan 12, to decelerate to 0.0 RPM. Once the RPM of motor 20 isat 0.0 RPM, the “Fan-Hold Mode” is implemented to allow VFD device 22and motor 20 hold the fan 12 at 0.0 RPM under power. A fan lockmechanism is then applied to motor shaft 24. All forms of energy (e.g.electrical energy) are then removed so as to lock out VFD 22 and motor20. Operator or user interaction can then take place. The fan lockmechanism can be either manually, electrically, mechanically orpneumatically operated, and either mounted to or built-in to motor 20.This fan lock will mechanically hold and lock the motor shaft 24 therebypreventing the fan 12 from rotating when power is removed. Such a fanlock can be used for LOTO as well as hurricane service. Fan lockconfigurations are discussed in the ensuing description. Once themaintenance procedures are completed on the fan or cooling tower, allsafety guards are replaced, the fan lock is released and the mechanicaldevices are returned to normal operation. The operator then unlocks andpowers up VFD device 22. Once power is restored, the operator uses thekeypad of DAQ device 200 to restart and resume fan operation. This LOTOcapability is a direct result of motor 20 being directly coupled to fanhub 16. The LOTO procedure provides reliable control of fan 12 and issignificantly safer than prior art techniques. This LOTO procedurecomplies with the National Safety Council and OSHA guidelines forremoval of all forms of energy.

One example of a fan lock mechanism that may be used on motor 20 isshown in FIGS. 21A, 21B and 21C. The fan lock mechanism is asolenoid-actuated pin-lock system and comprises enclosure or housing1200, which protects the inner components from environmental conditions,stop-pin 1202 and solenoid or actuator 1204. The solenoid or actuator1204 receives an electrical actuation signal from DAQ device 200 when itis desired to prevent fan rotation. The fan lock mechanism may bemounted on the drive portion of motor shaft 24 that is adjacent the fanhub, or it may be mounted on the lower, non-drive portion of the motorshaft 24. FIG. 21B shows solenoid 1204 so that stop-pin 1202 engagesrotatable shaft 24 of motor 20 so as to prevent rotation of shaft 24 andthe fan. In FIG. 21A, solenoid 1204 is deactivated so that stop pin 1202is disengaged from rotatable shaft 24 so as to allow rotation of shaft24 and the fan. FIG. 21C shows the fan-lock mechanism on both the upper,drive end of shaft 24, and the lower, non-drive end of shaft 24.

In an alternate embodiment, the fan-lock mechanism shown in FIGS. 21Aand 21B can be cable-actuated. In a further embodiment, the fan-lockmechanism shown in FIGS. 21A and 21B is actuated by a flexible shaft. Inyet another embodiment, the fan-lock mechanism shown in FIGS. 21A and21B is motor-actuated.

Referring to FIG. 22, there is shown a caliper type fan-lock mechanismwhich can be used with motor 20. This caliper type fan lock mechanismcomprises cover 1300 and a caliper assembly, indicated by referencenumbers 1302 and 1303. The caliper type fan lock mechanism also includesdiscs 1304 and 1305, flexible shaft cover 1306 and a shaft or threadedrod 1308 that is disposed within the flexible shaft cover 1306. Thecaliper type fan lock mechanism further includes fixed caliper block1310 and movable caliper block 1311. In an alternate embodiment, a cableis used in place of the shaft or threaded rod 1308. In alternateembodiments, the fan lock mechanism can be activated by a motor (e.g.screw activated) or a pull-type locking solenoid. FIG. 22 shows the fanlock mechanism mounted on top of the motor 20 so it can engage the upperportion of motor shaft 24. FIG. 23 shows the fan lock mechanism mountedat the bottom of motor 20 so the fan lock mechanism can engage thelower, non-drive end 25 of motor shaft 24. This caliper-type fan-lockmechanism comprises housing or cover 1400 and a caliper assembly,indicated by reference numbers 1402 and 1404. This caliper-type fan-lockmechanism includes disc 1406, flexible shaft cover 1410 and shaft orthreaded rod 1408 that is disposed within the flexible shaft cover 1410.

Referring to FIG. 25, there is shown a band-type fan-lock mechanismwhich can be used with motor 20. This band-type fan lock mechanismcomprises cover 1600, flexible shaft cover 1602 and a shaft or threadedrod 1604 that is disposed within the flexible shaft cover 1604. Theband-type fan lock mechanism further includes fixed lock bands 1606 and1610 and lock drum 1608. In an alternate embodiment, a cable is used inplace of the shaft or threaded rod 1604. In alternate embodiments, theband-type fan lock mechanism can be activated by a motor (e.g. screwactivated) or a pull-type locking solenoid. FIG. 25 shows the fan lockmechanism mounted on top of the motor 20 so it can engage the upperportion of motor shaft 24. FIG. 24 shows the fan lock mechanism mountedat the bottom of motor 20 so the fan lock mechanism can engage thelower, non-drive end 25 of motor shaft 24.

In another embodiment, the fan lock is configured as the fan lockdescribed in U.S. Patent Application Publication No. 2006/0292004, thedisclosure of which published application is hereby incorporated byreference.

De-Ice Mode

The variable process control system and motor 20 are also configured toimplement a “De-Ice Mode” of operation wherein the fan is operated inreverse. Icing of the fans in a cooling tower may occur depending uponthermal demand (i.e. water from the industrial process and the returndemand) on the tower and environmental conditions (i.e. temperature,wind and relative humidity). Operating cooling towers in freezingweather is described in the January, 2007 “Technical Report”, publishedby SPX Cooling Technologies. The capability of motor 20 to operate inreverse in order to reverse the fan direction during cold weather willde-ice the tower faster and completely by retaining warm air in thecooling tower as required by the environmental conditions. Motor 20 canoperate in reverse without limitations in speed and duration. However,prior art gear boxes are not designed to operate in reverse due to thelimitations of the gearbox's bearing and lubrication systems. One priorart technique is to add lubrication pumps (electrical and gerotor) tothe prior art gearbox in order to enable lubrication in reverseoperation. However, even with the addition of a lubrication pump, thegearboxes are limited to very slow speeds and are limited to a typicalduration of no more than two minutes in reverse operation due to thebearing design. For most cooling towers, the fans operate continuouslyat 100% fan speed. In colder weather, the additional cooling resultingfrom the fans operating at 100% fan speed actually causes the coolingtower to freeze which can lead to collapse of the tower. One prior arttechnique utilized by cooling tower operators is the use of two-speedmotors to drive the fans. With such a prior art configuration, thetwo-speed motor is continually jogged in a forward rotation and in areverse rotation in the hopes of de-icing the tower. In some cases, thegearboxes are operated beyond the two minute interval in order toperform de-icing. However, such a technique results in gearbox failureas well as icing damage to the tower. If the motors are shut off tominimize freezing of the towers, the fan and its mechanical system willice and freeze. Another prior art technique is to de-ice the towers lateat night with fire hoses that draw water from the cooling tower basin.However, this is a dangerous practice and often leads to injuries topersonnel. In order to solve the problems of icing in a manner thateliminates the problems of prior art de-icing techniques, the presentinvention implements an automatic de-icing operation without operatorinvolvement and is based upon the cooling tower thermal design, thermalgradient data, ambient temperature, relative humidity, wet-bulbtemperature, wind speed and direction. Due to the bearing design andarchitecture of motor 20 and design torque, fan 12 is able to rotate ineither direction (forward or reverse). This important feature enablesthe fan 12 to be rotated in reverse for purposes of de-icing. DAQ device200 and VFD device 22 are configured to operate motor 20 at variablespeed which will reduce icing in colder weather. This variable speedcharacteristic combined with design torque and fan speed operation inforward or reverse minimizes and eliminates icing of the tower. DAQdevice 200 is programmed with temperature set points, tower designparameters, plant thermal loading, and environmental conditions and usesthis programmed data and the measured temperature values provided by thetemperature sensors to determine if de-icing is necessary. If DAQ device200 determines that de-icing is necessary, then the de-icing mode isautomatically initiated without operator involvement. When suchenvironmental conditions exist, DAQ device 200 generates control signalsthat cause VFD device 22 to ramp down the RPM of motor 20 to 0.0 RPM.The Soft-Stop Mode can be used to ramp the motor RPM down to 0.00 RPM.Next, the motor 20 is operated in reverse so as to rotate the fan 12 inreverse so as to de-ice the cooling tower. The Reverse Flying Start modecan be used to implement de-icing. Since motor 20 does not have thelimitations of prior art gearboxes, supervision in this automatic de-icemode is not necessary. Upon initiation of de-icing, DAQ device 200issues a signal to industrial computer 300. In response, display screen306 displays a notice that informs the operators of the de-icingoperation. This de-icing function is possible because motor 20 comprisesa unique bearing design and lubrication system that allows unlimitedreverse operation (i.e. 100% fan speed in reverse) without durationlimitations. The unlimited reverse operation in combination withvariable speed provides operators or end users with infinite speed rangein both directions to match ever changing environmental stress (wind andtemperatures) while meeting process demand. Since DAQ device 200 can beprogrammed, the de-icing program may be tailored to the specific designof a cooling tower, the plant thermal loading and the surroundingenvironment. In a preferred embodiment, DAQ device 200 generates emailor SMS text messages to notify the operators of initiation of the de-icemode. In a preferred embodiment, DAQ device 200 generates a de-icingschedule based on the cooling tower design, the real time temperature,wet-bulb temperature, wind speed and direction, and other environmentalconditions. In an alternate embodiment, temperature devices maybeinstalled within the tower to monitor the progress of the de-icingoperation or to trigger other events. The variable process controlsystem of the present invention is configured to allow an operator tomanually initiate the De-Ice mode of operation. The software of the DAQdevice 200 and industrial computer 300 allows the operator to use eitherthe keypad at the DAQ device 200, or user input device 304 which is indata signal communication with industrial computer 300. In alternateembodiment, the operator initiates the De-Icing mode via DistributedControl System 315. In such an embodiment, the control signals arerouted to industrial computer 300 and then DAQ device 200.

In a multi-cell system, there is a separate VFD device for eachpermanent magnet motor but only one DAQ device for all of the cells.This means that every permanent magnet motor, whether driving a fan orpart a variable speed pump, will receive control signals from aseparate, independent, dedicated VFD device. Such a multi-cell system isdescribed in detail in the ensuing description. The DAQ device isprogrammed with the same data as described in the foregoing descriptionand further includes data representing the number of cells. The DAQdevice controls each cell individually such that certain cells may bedwelled, idled, held at stop or allowed to windmill while others mayfunction in reverse at a particular speed to de-ice the tower dependingupon the particular design of the cooling tower, outside temperature,wet bulb, relative humidity, wind speed and direction. Thus, the DAQdevice determines which cells will be operated in the de-ice mode.Specifically, DAQ device 200 is programmed so that certain cells willautomatically start de-icing the tower by running in reverse based uponthe cooling tower design requirements. Thus, the fan in each cell can beoperated independently to retain heat in the tower for de-icing whilemaintaining process demand.

In either the single fan cooling tower, or a multi-cell tower,temperature sensors in the cooling towers provide temperature data tothe DAQ device 200 processes these signals to determine if the De-Icemode should be implemented. In a multi-cell tower, certain cells mayneed de-icing and other cells may not. In that case, the DAQ devicesends the de-icing signals to only the VFDs that correspond to fan cellsrequiring de-icing.

The DAQ device is also programmed to provide operators with the optionof just reducing the speed of the fans in order to achieve some level ofde-icing without having to stop the fans and then operate in reverse.

In another embodiment of the invention, VFD device 22 is configured as aregenerative (ReGen) drive device. A regenerative VFD is a special typeof VFD with power electronics that return power to the power grid. Sucha regenerative drive system captures any energy resulting from the fan“windmilling” and returns this energy back to the power grid.“Windmilling” occurs when the fan is not powered but is rotating inreverse due to the updraft through the cooling tower. The updraft iscaused by water in the cell. Power generated from windmilling can alsobe used to limit fan speed and prevent the fan from turning during highwinds, tornados and hurricanes. The regenerative VFD device is alsoconfigured to generate control signals to motor 20 that to hold the fanat 0.00 RPM so as to prevent windmilling in high winds such as thoseexperienced during hurricanes.

Referring to FIG. 2, the variable process control system of the presentinvention further comprises a plurality of sensors and other measurementdevices that are in electrical signal communication with DAQ device 200.Each of these sensors has a specific function. Each of these functionsis now described in detail. Referring to FIGS. 4 and 5B, motor 20includes vibration sensors 400 and 402 which are located within motorcasing 21. Sensor 400 is positioned on bearing housing 50 and sensor 402is positioned on bearing housing 52. In a preferred embodiment, eachsensor 400 and 402 is configured as an accelerometer, velocity anddisplacement. As described in the foregoing description, sensors 400 and402 are electrically connected to quick-disconnect adapter 108 and cable110 is electrically connected to quick-disconnect adapter 108 andcommunication data junction box 111. Cable 112 is electrically connectedbetween communication data junction box 111 and DAQ device 200.Vibration sensors 400 and 402 provide signals that represent vibrationsexperienced by fan 12. Vibrations caused by a particular source orcondition have a unique signature. All signals emanating from sensors400 and 402 are inputted into DAQ device 200 which processes thesesensor signals. Specifically, DAQ device 200 includes a processor thatexecutes predetermined vibration-analysis algorithms that process thesignals provided by sensors 400 and 402 to determine the signature andsource of the vibrations. Such vibration-analysis algorithms include aFFT (Fast Fourier Transform). Possible reasons for the vibrations may bean unbalanced fan 12, instability of motor 20, deformation or damage tothe fan system, resonant frequencies caused by a particular motor RPM,or instability of the fan support structure, e.g. deck. If DAQ device200 determines that the vibrations sensed by sensors 400 and 402 arecaused by a particular RPM of motor 20, DAQ device 200 generates alock-out signal for input to VFD device 22. The lock-out signal controlsVFD device 22 to lock out the particular motor speed (or speeds) thatcaused the resonant vibrations. Thus, the lock-out signals prevent motor20 from operating at this particular speed (RPM). DAQ device 200 alsoissues signals that notify the operator via DCS 315. It is possible thatthere may be more than one resonant frequency and in such a case, allmotor speeds causing such resonant frequencies are locked out. Thus, themotor 20 will not operate at the speeds (RPM) that cause these resonantfrequencies. Resonant frequencies may change over time. However,vibration sensors 400 and 402, VFD device 22 and DAQ device 200constitute an adaptive system that adapts to the changing resonantfrequencies. The processing of the vibration signals by DAQ device 200may also determine that fan balancing may be required or that fan bladesneed to be re-pitched.

Fan trim balancing is performed at commissioning to identify fanimbalance, which is typically a dynamic imbalance. Static balance is thenorm. Most fans are not dynamically balanced. This imbalance causes thefan to oscillate which results in wear and tear on the tower, especiallythe bolted joints. In prior art fan drive systems, measuring fanimbalance can be performed but requires external instrumentation to beapplied to the outside of the prior art gearbox. This technique requiresentering the cell. However, unlike the prior art systems, DAQ device 200continuously receives signals outputted by vibration sensors 400 and402. Dynamic system vibration can be caused by irregular fan pitch, fanweight and or installation irregularities on the multiple fan bladesystems. Fan pitch is usually set by an inclinometer at commissioningand can change over time causing fan imbalance. If the pitch of any ofthe fan blades 18 deviates from a predetermined pitch or predeterminedrange of pitches, then a maintenance action will be performed on fanblades 18 in order to re-pitch or balance the blades. In a preferredembodiment, additional vibration sensors 404 and 406 are located onbearing housings 50 and 52, respectively, of motor 20 (see FIG. 4). Eachvibration sensor 404 and 406 is configured as an accelerometer or avelocity probe or a displacement probe. Each vibration sensor 404 and406 has a particular sensitivity and a high fidelity that is appropriatefor detecting vibrations resulting from fan imbalance. Signals emanatingfrom sensors 404 and 406 are inputted into DAQ device 200 via cable 110,communication data junction box 111 and cable 112. Sensors 404 and 406provide data that allows the operators to implement correct fan trimbalancing. Fan trim balancing provides a dynamic balance of fan 12 thatextends cooling tower life by reducing or eliminating oscillation forcesor the dynamic couple that causes wear and tear on structural componentscaused by rotating systems that have not been dynamically balanced. Ifthe measured vibrations indicate fan imbalance or are considered to bein a range of serious or dangerous vibrations indicating damaged bladesor impending failure, then DAQ device 200 automatically issues anemergency stop signal to VFD device 20. If the vibrations are serious,then DAQ device 200 issues control signals to VFD device 22 that causesmotor 20 to coast to a stop. The fan would be held using the Fan-Holdmode of operation. Appropriate fan locking mechanisms would be appliedto the motor shaft 24 so that the fan could be inspected and serviced.DAQ device 200 then issues alert notification via email or SMS textmessages to the DCS 315 to inform the operators that then fan has beenstopped due to serious vibrations. DAQ device 200 also issues thenotification to industrial computer 300 for display on display 306. Ifthe vibration signals indicate fan imbalance but the imbalance is not ofa serious nature, DAQ device 200 issues a notification to the DCS 315 toalert the operators of the fan imbalance. The operators would have theoption cease operation of the cooling tower or fan cell so that the fancan be inspected and serviced if necessary. Thus, the adaptivevibration-monitoring and compensation function of the variable processcontrol system of the present invention combines with the bearing designand structure of motor 20 to provide low speed, dynamic fan trim balancethereby eliminating the “vibration couple”.

The adaptive vibration feature of the variable process control systemprovides 100% monitoring, supervision and control of the direct drivefan system with the capability to issue reports and alerts to DCS 315via e-mail and SMS. Such reports and alerts notify operators ofoperating imbalances, such as pitch and fan imbalance. Large vibrationsassociated with fan and hub failures, which typically occur within acertain vibration spectrum, will result in motor 20 being allowed toimmediately coast down to 0.0 RPM. The fan-hold mode is thenimplemented. Industrial computer 300 then implements FFT processing ofthe vibration signals in order to determine the cause of the vibrationsand to facilitate prediction of impeding failures. As part of thisprocessing, the vibration signals are also compared to historic trendingdata in order to facilitate understanding and explanation of the causeof the vibrations.

In an alternate embodiment, the variable process control system of thepresent invention uses convenient signal pick-up connectors at severallocations outside the fan stack. These signal pick-up connectors are insignal communication with sensors 400 and 402 and can be used byoperators to manually plug in balancing equipment (e.g. Emerson CSI2130) for purposes of fan trim.

In accordance with the invention, when sensors 400, 402, 404 and 406 arefunctioning properly, the sensors output periodic status signals to DAQdevice 200 in order to inform the operators that sensors 400, 402, 404and 406 are working properly. If a sensor does not emit a status signal,DAQ device 200 outputs a sensor failure notification that is routed toDCS 315 via email or SMS text messages. The sensor failure notificationsare also displayed on display screen 306 to notify the operators of thesensor failure. Thus, as a result of the continuous 100% monitoring ofthe sensors, lost sensor signals or bad sensor signals will cause analert to be issued and displayed to the operators. This feature is asignificant improvement over prior art systems which require an operatorto periodically inspect vibration sensors to ensure they are workingproperly. When a sensor fails in a prior art fan drive system, there isno feedback or indication to the operator that the sensor has failed.Such deficiencies can lead to catastrophic results such as catastrophicfan failure and loss of the cooling tower asset. However, the presentinvention significantly reduces the chances of such catastrophicincidents from ever occurring. In the present invention, there isbuilt-in redundancy with respect to the sensors. In a preferredembodiment, all sensors are Line Replaceable Units (LRU) that can easilybe replaced. In a preferred embodiment, the Line Replaceable Unitsutilize area classified Quick Disconnect Adapters such as the TurckMultifast Right Angle Stainless Connector with Lokfast Guard, which wasdescribed in the foregoing description.

Examples of line replaceable vibration sensor units that are used todetect vibrations at motor 20 are shown in FIGS. 18, 19 and 20.Referring to FIG. 18, there is shown a line-replaceable vibration sensorunit that is in signal communication with instrument junction box 900that is connected to motor housing or casing 21. This vibration sensorunit comprises cable gland 902, accelerometer cable 904 which extendsacross the exterior surface of the upper portion 906 of motor casing 21.Accelerometer 908 is connected to upper portion 906 of motor casing 21.In a preferred embodiment, accelerometer 908 is connected to upperportion 906 of motor casing 21 with a Quick Disconnect Adapters such asthe Turck Multifast Right Angle Stainless Connector with Lokfast Guardwhich was described in the foregoing description. Sensor signals fromaccelerometer 908 are received by DAQ device 200 for processing. In apreferred embodiment, sensor signals from accelerometer 908 are providedto DAQ device 200 via instrument junction box 900. In such anembodiment, instrument junction box 900 is hardwired to DAQ device 200.

Another line-replaceable vibration sensor unit is shown in FIG. 19. Thisline-replaceable vibration sensor unit that is in signal communicationwith instrument junction box 900 that is connected to motor housing orcasing 21 and comprises cable gland 1002, and accelerometer cable 1004which extends across the exterior surface of the upper portion 1006 ofmotor casing 21. This vibration sensor unit further comprisesaccelerometer 1008 that is joined to upper portion 1006 of motor casing21. Accelerometer 1008 is joined to upper portion 1006 of motor casing21. In a preferred embodiment, accelerometer 1008 is hermetically sealedto upper portion 1006 of motor casing 21. Sensor signals fromaccelerometer 1008 are received by DAQ device 200 for processing. In oneembodiment, sensor signals from accelerometer 1008 are provided to DAQdevice 200 via instrument junction box 900. In such an embodiment,instrument junction box 900 is hardwired to DAQ device 200.

Another line-replaceable vibration sensor unit is shown in FIG. 20. Thisline-replaceable vibration sensor unit that is in signal communicationwith instrument junction box 900 that is connected to motor housing orcasing 21 and comprises cable gland 1102, and accelerometer cable 1104which extends across the exterior surface of the upper portion 1110 ofmotor casing 21. This vibration sensor unit further comprisesaccelerometer 1108 that is joined to upper portion 1110 of motor casing21. Accelerometer 1108 is joined to upper portion 1100 of motor casing21. In a preferred embodiment, accelerometer 1108 is hermetically sealedto upper portion 1100 of motor casing 21. Sensor signals fromaccelerometer 1108 are received by DAQ device 200 for processing. In oneembodiment, sensor signals from accelerometer 1108 are provided to DAQdevice 200 via instrument junction box 900. In such an embodiment,instrument junction box 900 is hardwired to DAQ device 200.

It is to be understood that in alternate embodiments, one or morevibrations sensors can be mounted to the motor structure, or mounted tothe exterior of the motor, or mounted on the exterior of the motorhousing or casing, or mounted to instrumentation boxes or panels thatare attached to the exterior of the motor. In an alternate embodiment,additional vibration sensors can be mounted to the cooling towerstructure at various locations.

Referring to FIGS. 2 and 4, the variable process control system of thepresent invention further comprises a plurality of temperature sensorsthat are positioned at different locations within the variable processcontrol system and within cooling apparatus 10. In a preferredembodiment, each temperature sensor comprises a commercially availabletemperature probe. Each temperature sensor is in electrical signalcommunication with communication data junction box 111. Temperaturesensors located within motor casing 21 are electrically connected toquick-disconnect adapter 108 which is in electrical signal communicationwith communication data junction box 111 via wires 110. The temperaturesensors that are not located within motor casing 21 are directlyhardwired to communication data junction box 111. The functions of thesesensors are as follows:

-   -   1) sensor 420 measure the temperature of the interior of motor        casing 21 (see FIG. 4);    -   2) sensors 421A and 421B measure the temperature of the motor        bearing housings 50 and 52, respectively (see FIG. 4);    -   3) sensor 422 measures the temperature of stator 32, the end        turns of the coils or windings, the laminations, etc. that are        within the motor casing 21 (see FIG. 4);    -   4) sensor 426 is located near motor casing 21 to measure the        ambient temperature of the air surrounding motor 20 (see FIG.        2);    -   5) sensor 428 is located in a collection basin (not shown) of a        wet-cooling tower to measure the temperature of the water in the        collection basin (see FIG. 2);    -   6) sensor 430 measures the temperature at DAQ device 200 (see        FIGS. 2 and 4);    -   7) sensor 432 measures the wet-bulb temperature (see FIG. 2);    -   8) sensor 433 measures the temperature of the airflow created by        the fan (see FIG. 4);    -   9) sensor 434 measures the external temperature of the motor        casing (see FIG. 4);    -   10) sensor 435 detects gas leaks or other emissions (see FIG.        4).        In a preferred embodiment, there is a plurality of sensors that        perform each of the aforesaid tasks. For example, in one        embodiment, there are is plurality of sensors 428 that measure        the temperature of the water in the collection basin.

Sensors 426, 428, 430, 432, 433, 434 and 435 are hard wired directly tocommunication data junction box 111 and the signals provided by thesesensors are provided to DAQ device 200 via cable 112. Since sensors421A, 421B and 422 are within motor casing 21, the signals from thesesensors are fed to quick-disconnect adapter 108. The internal wires inmotor 20 are not shown in FIG. 2 in order to simplify the diagram shownin FIG. 2. A sudden rise in the temperatures of motor casing 21 or motorstator 32 (stator, rotor, laminations, coil, end turns) indicates a lossof airflow and/or the cessation of water to the cell. If such an eventoccurs, DAQ device 200 issues a notification to the plant DCS 315 andalso simultaneously activates alarms, such as alarm device 438 (see FIG.2), and also outputs a signal to industrial computer 300. This featureprovides a safety mechanism to prevent motor 20 from overheating.

In an alternate embodiment, sensor 430 is not hardwired to communicationdata junction box 111, but instead, is directly wired to the appropriateinput of DAQ device 200.

Thus, DAQ device 200, using the aforesaid sensors, measures theparameters set forth in Table I:

TABLE I Parameter Measured Purpose Internal motor temperature:Monitoring, supervision, health analysis; end turns, coil lamination,detect motor overheating; detect wear or stator, internal air and damageof coil, stator, magnets; detect magnets lack of water in cell Externalmotor temperature Monitoring, supervision, health analysis; detect motoroverheating; detect lack of water in cell Bearing TemperatureMonitoring, supervision, health analysis; detect bearing wear orimpending failure; detect lubrication issues; FFT processing Fan StackTemperature Monitoring, supervision, health analysis; determine CoolingTower Thermal Capacity; determine existence of icing; operationalanalysis Plenum Pressure Monitoring, supervision, health analysis;plenum pressure equated to fan inlet pressure for mass airflowcalculation Motor Load Cells Determine fan yaw loads; system weight;assess bearing life; FFT processing Bearing Vibration Monitoring,supervision, health analysis; trim balance; adaptive vibrationmonitoring; modal testing Gas Leaks or Emissions Monitoring,supervision, health analysis; detect fugitive gas emissions; monitoringheat exchanger and condenser for gas emissions

The desired temperature of the liquid in the collection basin, alsoknown as the basin temperature set-point, can be changed by theoperators instantaneously to meet additional cooling requirements suchas cracking heavier crude, maintain vacuum backpressure in a steamturbine, prevent fouling of the heat exchanger or to derate the plant topart-load. Industrial computer 300 is in electronic signal communicationwith the plant DCS (Distributed Control System) 315 (see FIG. 2). Theoperators use plant DCS 315 to input the revised basin temperatureset-point into industrial computer 300. Industrial computer 300communicated this information to DAQ device 200. Sensor 428 continuouslymeasures the temperature of the liquid in the collection basin in orderto determine if the measure temperature is above or below the basintemperature set-point. DAQ device 200 processes the temperature dataprovided by sensor 428, the revised basin temperature set point, thecurrent weather conditions, thermal and process load, and pertinenthistorical data corresponding to weather, time of year and time of day.

In one embodiment, wet-bulb temperature is measured with suitableinstrumentation such as psychrometers, thermohygrometers or hygrometerswhich are known in the art.

As a result of the adaptive characteristics of the variable processcontrol system of the present invention, a constant basin temperature ismaintained despite changes in process load, Cooling Tower ThermalCapacity, weather conditions or time of day. DAQ device 200 continuouslygenerates updated sinusoidal fan speed curve in response to the changingprocess load, Cooling Tower Thermal Capacity, weather conditions or timeof day.

Temperature sensor 430 measures the temperature at DAQ device 200 inorder to detect overheating cause by electrical overload, short circuitsor electronic component failure. In a preferred embodiment, ifoverheating occurs at DAQ device 200, then DAQ device 200 issues anemergency stop signal to VFD device 22 to initiate an emergency “SoftStop Mode” to decelerate motor 20 to 0.00 RPM and to activate alarms(e.g. alarm 438, audio alarm, buzzer, siren, horn, flashing light, emailand text messages to DCS 315, etc.) to alert operators to the fact thatthe system is attempting an emergency shut-down procedure due toexcessive temperatures. In one embodiment of the present invention, ifoverheating occurs at DAQ device 200, DAQ device 200 issues a signal toVFD device 22 to maintain the speed of motor 20 at the current speeduntil the instrumentation can be inspected.

The operating parameters of motor 20 and the cooling tower areprogrammed into DAQ device 200. DAQ device 200 comprises amicroprocessor or mini-computer and has computer processing power. Manyof the operating parameters are defined over time and are based on theoperating tolerances of the system components, fan and tower structure.Gradual heating of motor 20 (stator, rotor, laminations, coil, endturns, etc.) in small increments as determined by trending over months,etc. as compared with changes (i.e. reductions) in horsepower or fantorque over the same time interval, may indicate problems in the coolingtower such as clogged fill, poor water distribution, etc. Industrialcomputer 300 will trend the data and make a decision as to whether todisplay a notice on display 306 that notifies the operators that aninspection of the cooling tower is necessary. A sudden rise in motortemperature as a function of time may indicate that the cell water hasbeen shut-off. Such a scenario will trigger an inspection of the tower.The variable process control system of the present invention is designedto notify operators of any deviation from operating parameters. Whendeviations from these operating parameters and tolerances occur(relative to time), DAQ device 200 issues signals to the operators inorder to notify them of the conditions and that an inspection isnecessary. Relative large deviations from the operating parameters, suchas large vibration spike or very high motor temperature, would cause DAQdevice 200 to generate a control signal to VFD device 22 that willenable motor 20 to coast to complete stop. The fan is then held by theFan Hold mode of operation. DAQ device 200 simultaneously issues alertsand notifications via email and/or text messages to DCS 315.

As described in the foregoing description, VFD device 22, DAQ device 200and industrial computer 300 are housed in Motor Control Enclosure (MCE)26. The variable process control system includes a purge system thatmaintains a continuous positive pressure on cabinet 26 in order toprevent potentially explosive gases from being drawn into MCE 26. Suchgases may originate from the heat exchanger. The purge system comprisesa compressed air source and a device (e.g. hose) for delivering acontinuous source of pressurized air to MCE 26 in order to create apositive pressure which prevents entry of such explosive gases. In analternate embodiment, MCE 26 is cooled with Vortex coolers that utilizecompressed air. In a further embodiment, area classified airconditioners are used to deliver airflow to MCE 26.

Referring to FIG. 2, in a preferred embodiment, the system of thepresent invention further includes at least one pressure measurementdevice 440 that is located on the fan deck and which measures thepressure in the cooling tower plenum. In a preferred embodiment, thereis a plurality of pressure measurement devices 400 to measure thepressure in the cooling tower plenum. Each pressure measurement device440 is electrically connected to communication data junction box 111.The measured pressure equates to the pressure before the fan (i.e. faninlet pressure). The measured pressure is used to derive fan pressurefor use in cooling performance analysis.

It is critical that the fan be located at the correct fan height inorder to produce the requisite amount of design fan pressure. The fanmust operate at the narrow part of the fan stack in order to operatecorrectly, as shown in FIG. 13. Many prior art fan drive systems do notmaintain the correct fan height within the existing parabolic fan stackinstallation. Such a misalignment in height causes significantdegradation in cooling capacity and efficiency. An important feature ofthe load bearing direct drive fan system of the present invention isthat the design architecture of motor 20 maintains or corrects the fanheight in the fan stack. Referring to FIGS. 13 and 14, there is shown adiagram of a wet cooling tower that uses the load bearing direct drivefan system of the present invention. The wet cooling tower comprises fanstack 14 and fan deck 250. Fan stack 14 is supported by fan deck 250.Fan stack 14 has a generally parabolic shape. In other embodiments, fanstack 14 can have a straight cylinder shape (i.e. cylindrical shape).Fan stack 14 and fan deck 250 were discussed in the foregoingdescription. A parabolic fan stack 14 requires that the motor heightaccommodate the proper fan height in the narrow throat section of fanstack 14 in order to seal the end of the fan blade at the narrow pointof the parabolic fan stack 14. This assures that the fan will operatecorrectly and provide the proper fan pump head for the application. Thewet cooling tower includes fan assembly 12 which was described in theforegoing description. Fan assembly 12 comprises fan hub 16 and fanblades 18 that are connected to fan hub 16. Fan assembly 12 furthercomprises fan seal disk 254 that is connected to the top of fan hub 16.Fan hub 16 has a tapered bore 255. Motor 20 has a locking keyed shaft 24which interfaces with a complementary shaped portion of tapered bore255. Specifically, as shown in FIG. 14, motor shaft 24 is configured tohave a key channel 256 that receives a complementary shaped portion offan hub 16. Tapered bushing 257 is fastened to motor shaft 24 with setscrew 258 so as to prevent movement of tapered bushing 257. The height Hindicates the correct height at which the fan blades 18 should belocated (see FIG. 13) within fan stack 14. The height H indicates theuppermost point of the narrow portion of fan stack 14. This is thecorrect height at which the fan blades 18 should be located in order forthe fan assembly 12 to operate properly and efficiently. An optionaladapter plate 260 can be used to accurately position the fan blades 18at the correct height H (see FIGS. 13 and 14). Retrofitting motor 20 andadapter plate 260, as required, and correcting fan height can actuallyincrease airflow through the cooling tower by setting the fan assembly12 at the correct height H. Adapter plate 260 is positioned betweenladder frame/torque tube 262 and motor 20 such that motor 20 is seatedupon and connected to adapter plate 260. Motor 20 is connected to aladder frame or torque tube or other suitable metal frame that extendsover the central opening in the fan deck 250. Motor 20 is designed suchthat only four bolts are needed to connect motor 20 to the existingladder frame or torque tube. As shown in FIG. 12B, motor housing 21 hasfour holes 264A, 264B, 264C and 264D extending therethrough to receivefour mounting bolts. Adapter plate 260 is designed with correspondingthrough-holes that receive the aforementioned four bolts. The four boltsextend through corresponding openings 264A, 264B, 264C and 264D throughthe corresponding openings in adapter plate 260 and throughcorresponding openings in the ladder frame or torque tube. Thus, bydesign, the architecture of motor 20 is designed to be a drop-inreplacement for all prior art gearboxes (see FIG. 1) and maintains orcorrects fan height in the fan stack 14 without structural modificationsto the cooling tower or existing ladder frame or torque tubes. Such afeature and advantage is possible because motor 20 is designed to have aweight that is the same or less than the prior art gearbox system itreplaces. The mounting configuration of motor 20 (see FIG. 12B) allowsmotor 20 to be mounted to existing interfaces on existing structuralladder frames and torque tubes and operate within the fan stack meetingArea Classification for Class 1, Div. 2, Groups B, C, D. Therefore, newor additional ladder frames and torque tubes are not required whenreplacing a prior art gearbox system with motor 20. Since motor 20 has aweight that is the same or less than the prior art gearbox it replaces,motor 20 maintains the same weight distribution on the existing ladderframe or torque tube 262. Motor 20 is connected to fan hub 16 in thesame way as a prior art gearbox is connected to fan hub 16. The onlycomponents needed to install motor 20 are: (a) motor 20 having powercable 105 wired thereto as described in the foregoing description,wherein the other end of power cable 105 is adapted to be electricallyconnected to motor disconnect junction box 106, (b) the four bolts thatare inserted into through-holes 264A, 264B, 264C and 264D in motorcasing or housing 21, (c) cable 110 having one terminated at aquick-disconnect adapter 108, and the other end adapted to beelectrically connected to communication data junction box 111 (d) powercable 107 which is adapted to be electrically connected to motordisconnect junction box 106 and VFD device 22. Power cables 105 and 107were described in the foregoing description. As a result of the designof motor 20, the process of replacing a prior art drive system withmotor 20 is simple, expedient, requires relatively less crane hours, andrequires relatively less skilled labor than required to install andalign the complex, prior art gearboxes, shafts and couplings. In apreferred embodiment, motor 20 includes lifting lugs or hooks 270 thatare rigidly connected to or integrally formed with motor housing 21.These lifting lugs 270 are located at predetermined locations on motorhousing 21 so that motor 20 is balanced when being lifted by a craneduring the installation process. Motor 20 and its mounting interfaceshave been specifically designed for Thrust, Pitch, Yaw, reverse loadsand fan weight (dead load).

Thus, motor 20 is specifically designed to fit within the installationenvelope of an existing, prior art gearbox and maintain or correct thefan height in the fan stack. In one embodiment, the weight of motor 20is less than or equal to the weight of the currently-usedmotor-shaft-gearbox drive system. In a preferred embodiment of theinvention, the weight of motor 20 does not exceed 2500 lbs. In oneembodiment, motor 20 has a weight of approximately 2350 lbs. Motor shaft24 has been specifically designed to match existing interfaces withfan-hub shaft diameter size, profile and keyway. Motor 20 can rotate allhubs and attaching fans regardless of direction, blade length, fansolidity, blade profile, blade dimension, blade pitch, blade torque, andfan speed.

It is to be understood that motor 20 may be used with other models ortypes of cooling tower fans. For example, motor 20 may be used with anyof the commercially available 4000 Series Tuft-Lite Fans manufactured byHudson Products, Corporation of Houston, Tex. In an alternateembodiment, motor 20 is connected to a fan that is configured without ahub structure. Such fans are known are whisper-quiet fans orsingle-piece wide chord fans. The single-piece wide chord fan operatesat slower speeds for noise attenuation. The single-piece wide chord fanhas no fan hub and is of a direct-bolt configuration. When single-piecewide chord fans are used, rotatable motor shaft 24 is directly bolted orconnected to the fan. One commercially available whisper-quiet fan isthe PT2 Cooling Tower Whisper Quiet Fan manufactured by BaltimoreAircoil Company of Jessup, Md.

Motor 20 is designed to withstand the harsh chemical attack, poor waterquality, mineral deposits and pH attack, biological growth, and humidenvironment without contaminating the lubrication system or degradingthe integrity of motor 20. Motor 20 operates within the fan stack anddoes not require additional cooling ducts or flow scoops.

For a new installation (i.e. newly constructed cooling tower), theinstallation of motor 20 does not require ladder frames and torque tubesas do prior art gearbox systems. The elimination of ladder frames andtorque tubes provides a simpler structure at a reduced installationcosts. The elimination of the ladder frame and torque tubessignificantly reduces obstruction and blockage from the supportstructure thereby reducing airflow loss. The elimination of ladderframes and torque tubes also reduce fan pressure loss and turbulence.The installation of motor 20 therefore is greatly simplified andeliminates multiple components, tedious alignments, and also reducesinstallation time, manpower and the level of skill of the personnelinstalling motor 20. The electrical power is simply connected at motorjunction box 106. The present invention eliminates shaft penetrationthrough the fan stack thereby improving fan performance by reducingairflow loss and fan pressure loss.

As described in the foregoing description, cable 105 is terminated orprewired at motor 20 during the assembly of motor 20. Such aconfiguration simplifies the installation of motor 20. Otherwise,confined-space entry training and permits would be required for anelectrician to enter the cell to install cable 105 to motor 20.Furthermore, terminating cable 105 to motor 20 during the manufacturingprocess provides improved reliability and sealing of motor 20 since thecable 105 is assembled and terminated at motor 20 under cleanconditions, with proper lighting and under process and quality control.If motor 20 is configured as a three-phase motor, then cable 105 iscomprised of three wires and these three wires are to be connected tothe internal wiring within motor disconnect junction box 106.

Test Results

-   -   The system of the present invention was implemented with a        wet-cooling tower system. Extensive Beta Testing was conducted        on the system with particular attention being directed to        vibrations and vibration analysis. FIG. 11A is a bearing        vibration report, in graph form, which resulted from a beta test        of the system of the present invention. FIG. 11B is the same        bearing vibration report of FIG. 11A and shows a prior art (i.e.        gearbox) trip value of 0.024 G. FIG. 11C is a vibration severity        graph showing the level of vibrations generated by the system of        the present invention. These test results reveal motor 20 and        its drive system operate significantly smoother than the prior        art gearbox systems thereby producing a significantly lower        vibration signature. Such smooth operation is due to the unique        bearing architecture of motor 20. The average operating range of        the motor 20 is 0.002 G with peaks of ±0.005 G as opposed to the        average prior art gearbox trip value of 0.024 G.

The aforementioned smooth operation of motor 20 and its drive systemallows accurate control, supervision, monitoring and system-healthmanagement because the variable process control system of the presentinvention is more robust. On the other hand, prior art gear-train meshes(i.e. motor, shaft, couplings and subsequent multiple gear-trainsignatures) have multiple vibration signatures and resultantcross-frequency noise that are difficult to identify and manageeffectively. Motor 20 increases airflow through a cooling tower byconverting more of the applied electrical energy into airflow because iteliminates the losses of the prior art gearbox systems and issignificantly more efficient than the prior art gearbox systems.

A common prior art technique employed by many operators of coolingtowers is to increase water flow into the cooling towers in order toimprove condenser performance. FIG. 17 shows a graph of approximatedcondenser performance. However, the added stress of the increased waterflow causes damage to the cooling tower components and actually reducescooling performance of the tower (L/G ratio). In some cases, it can leadto catastrophic failure such as the collapse of a cooling tower.However, with the variable process control system of the presentinvention, increasing water flow is totally unnecessary because thecooling tower design parameters are programmed into both DAQ device 200and industrial computer 300. Specifically, in the variable processcontrol system of the present invention, the cooling tower pumps andauxiliary systems are networked with the fans to provide additionalcontrol, supervision and monitoring to prevent flooding of the tower anddangerous off-performance operation. In such an embodiment, the pumpsare hardwired to DAQ device 200 so that DAQ device 200 controls theoperation of the fan, motor and pumps. In such an embodiment, pump-watervolume is monitored as a way to prevent the collapse of the tower underthe weight of the water. Such monitoring and operation of the pumps willimprove part-load cooling performance of the tower as the L/G ratio ismaximized for all load and environmental conditions. Such monitoring andoperation will also prevent flooding and further reduce energyconsumption. The flow rate through the pumps is a function of processdemand or the process of a component, such as the condenser process. Ina preferred embodiment, the variable process control system of thepresent invention uses variable speed pumps. In an alternate embodiment,variable frequency drive devices, similar to VFD device 22, are used tocontrol the variable speed pumps in order to further improve part-loadperformance. In a further embodiment, the cooling tower variable speedpumps are driven by permanent magnet motors that have the same orsimilar characteristics as motor 20.

Thus, the variable process control system of the present inventionoperates the fan at a constant speed and varies the speed of the fan tomaintain a constant basin temperature as the environmental and processdemand conditions change. The variable process control system of thepresent invention uses current wet-bulb temperature and environmentalstress and past process demand and past environmental stress toanticipate changes in fan speed, and accordingly ramp fan speed up orramp fan speed down in accordance with a sine wave (see FIG. 9) in orderto meet cooling demand. This important characteristic and feature savesenergy with relatively smaller and less frequent changes in fan speed.The variable process control system varies the speed of the fan tomaintain a constant basin temperature as environmental stress andprocess demands change and maintains pre-defined heat exchanger andturbine back-pressure set-points in the industrial process in order tomaintain turbine back-pressure and avoid heat exchanger fouling. Thevariable process control system also varies the speed of the fan and thespeed of the variable speed pumps to maintain a constant basintemperature as environmental stress and process demands change andmaintains pre-defined heat exchanger and turbine back-pressureset-points in the industrial process in order to maintain turbineback-pressure and avoid heat exchanger fouling. The variable processcontrol system of the present invention can also vary the speed of thefan to maintain a constant basin temperature as environmental stress andprocess conditions change and maintain pre-defined heat exchanger andturbine back-pressure set-points in the industrial process in order tomaintain turbine back-pressure and avoid heat exchanger fouling andprevent freezing of the cooling tower by either reducing fan speed oroperating the fan in reverse. The variable process control system of thepresent invention also can vary the speed of the fan to change basintemperature as environmental stress and process conditions change andmaintain pre-defined heat exchanger and turbine back-pressure set-pointsin the industrial process in order to maintain turbine back-pressure andavoid heat exchanger fouling AND prevent freezing of the cooling towerby either reducing fan speed or operating the fan in reverse. Thevariable process control system of the present invention can also varythe speed of the fan and the speed of the variable speed pumps to changethe basin temperature as environmental stress and process conditionschange and maintain turbine back-pressure and avoid heat exchangerfouling and prevent freezing of the cooling tower by either reducing fanspeed or operating the fan in reverse.

Referring to FIG. 26, there is shown a schematic diagram of the variableprocess control system and motor 20 of the present invention used with awet-cooling tower that is part of an industrial process. In thisembodiment, the variable process control system includes a plurality ofvariable speed pumps. In this embodiment, motor 20 is configured as theload bearing permanent magnet motor that was discussed in the foregoingdiscussion. Each variable speed pump comprises a load bearing permanentmagnet motor that has the same operational characteristics as thepermanent magnet motor that was discussed in the foregoing description.Thus, each variable speed pump comprises a permanent magnet motor thathas the same operational characteristics as motor 20. Wet-cooling tower1700 comprises tower structure 1702, fan deck 1704, fan stack 1706 andcollection basin 1708. Cooling tower 1700 includes fan 1710 andpermanent magnet motor 20 which drives fan 1710. Fan 1710 has the samestructure and function as fan 12 which was described in the foregoingdescription. Cooling tower 1700 includes inlet for receiving make-upwater 1712. The portion of cooling tower 1700 that contains the fillmaterial, which is well known in the art, is not shown in FIG. 26 inorder to simplify the drawing. Collection basin 1708 collects watercooled by fan 1710. Variable speed pumps pump the cooled water fromcollection basin 1708, to condenser 1714, and then to process 1716wherein the cooled water is used in an industrial process. It is to beunderstood that condenser 1714 is being used as an example and a similardevice, such as a heat exchanger, can be used as well. The condensertemperature set-point is typically set by the operators through theDistributed Control System 315 (see FIG. 3) via signal 1717. Theindustrial process may be petroleum refining, turbine operation, crudecracker, etc. The variable speed pumps also pump the heated water fromprocess 1716 back to condenser 1714 and then back to cooling tower 1700wherein the heated water is cooled by fan 1710. Cooled water exitingcollection basin 1708 is pumped by variable speed pump 1722 to condenser1714. Variable speed pump 1722 further includes an instrumentationmodule which outputs pump status data signals 1726 that represent theflow rate, pressure and temperature of water flowing through variablespeed pump 1722 and into condenser 1714. Data signals 1726 are inputtedinto DAQ device 200. This feature will be discussed in the ensuingdescription. Water exiting condenser 1714 is pumped to process 1716 byvariable speed pump 1730. Variable speed pump 1730 includes aninstrumentation module that outputs pump status data signals 1734 thatrepresent the flow rate, pressure and temperature of water flowingthrough variable speed pump 1730. Water leaving process 1716 is pumpedback to condenser by 1714 by variable speed pump 1738. Variable speedpump 1738 includes an instrumentation module which outputs pump statusdata signals 1742 that represent the flow rate, pressure and temperatureof water flowing through variable speed pump 1738. The water exitingcondenser 1714 is pumped back to cooling tower 1700 by variable speedpump 1752. Variable speed pump 1752 further includes an instrumentationmodule that outputs pump status data signals 1756 that represent theflow rate, pressure and temperature of water flowing through variablespeed pump 1752.

VFD device 22 comprises a plurality of Variable Frequency Devices.Specifically, VFD device 22 comprises VFD devices 23A, 23B, 23C, 23D and23E. VFD device 23A outputs power over power cable 107. Power cables 107and 105 are connected to junction box 106. Power cable 105 delivers thepower signals to motor 20. Power cables 105 and 107 and junction box 106were discussed in the foregoing description. VFD device 23B outputspower signal 1724 for controlling the permanent magnet motor of thevariable speed pump 1722. VFD device 23C outputs power signal 1732 forcontrolling the permanent magnet motor of the variable speed pump 1730.VFD device 23D outputs power signal 1740 for controlling the permanentmagnet motor of the variable speed pump 1738. VFD device 23E outputspower signal 1754 for controlling the permanent magnet motor of thevariable speed pump 1752. DAQ device 200 is in electronic signalcommunication with VFD devices 23A, 23B, 23C, 23D and 23E. DAQ device200 is programmed to control each VFD device 23A, 23B, 23C, 23D and 23Eindividually and independently. All variable speed pump output datasignals 1726, 1734, 1742 and 1756 from the variable speed pumps 1722,1730, 1738 and 1752, respectively, are inputted into DAQ device 200. DAQdevice 200 processes these signals to determine the process load andthermal load. DAQ device 200 determines the thermal load by calculatingthe differences between the temperature of the water leaving thecollection basin and the temperature of the water returning to thecooling tower. DAQ device 200 determines process demand by processingthe flow-rates and pressure at the variable speed pumps. Once DAQ device200 determines the thermal load and process load, it determines whetherthe rotational speed of the fan 1710 is sufficient to meet the processload. If the current rotational speed of the fan is not sufficient, DAQdevice 200 develops a fan speed curve that will meet the thermal demandand process demand. As described in the foregoing description, DAQdevice 200 uses Cooling Tower Thermal Capacity, current thermal demand,current process demand, current environmental stress, and historicaldata, such as historic process and thermal demand and historicenvironmental stress to generate a fan speed curve.

As shown in FIG. 26, DAQ device 200 also receives the temperature andvibration sensor signals that were discussed in the foregoingdescription. Typically, the basin temperature set-point is based on thecondenser temperature set-point which is usually set by the plantoperators. DAQ device 200 determines if the collection basin temperaturemeets the basin temperature set-point. If the collection basintemperature is above or below the basin temperature set-point, then DAQdevice 200 adjusts the rotational speed of motor 20 in accordance with arevised or updated fan speed curve. Therefore, DAQ device 200 processesall sensor signals and data signals from variable speed pumps 1722,1730, 1738 and 1752. DAQ device 200 is programmed to utilize theprocessed signals to determine if the speed of the variable speed pumpsshould be adjusted in order to increase cooling capacity for increasedprocess load, adjust the flow rate of water into the tower, preventcondenser fouling, maintain vacuum back-pressure, or adjust theflow-rate and pressure at the pumps for plant-part load conditions inorder to conserve energy. If speed adjustment of the variable speedpumps is required, DAQ device 200 generates control signals that arerouted over data bus 202 for input to VFD devices 23B, 23C, 23D and 23E.In response, these VFD devices 23B, 23C, 23D and 23E generate powersignals 1724, 1732, 1740 and 1754, respectively, for controlling thepermanent magnet motors of variable speed pumps 1722, 1730, 1738 and1752, respectively. DAQ device 200 controls each VFD devices 23A, 23B,23C, 23D and 23E independently. Thus, DAQ device 200 can increase thespeed of one variable speed pump while simultaneously decreasing thespeed of another variable speed pump and adjusting the speed of the fan1710.

In an alternate embodiment of the invention, all variable speed pumpoutput data signals 1726, 1734, 1742 and 1756 are not inputted into DAQdevice 200 but instead, are inputted into industrial computer 300 (seeFIG. 3) which processes the pump output data signals and then outputspump control signals directly to the VFD devices 23B, 23C, 23D and 23E.

Each instrumentation module of each variable speed pump includes sensorsfor measuring motor and pump vibrations and temperatures. The signalsoutputted by these sensors are inputted to DAQ device 200 forprocessing.

It is to be understood that instrumentation of than the aforesaidinstrumentation modules may be used to provide the pump status signals.The electrical power source for powering all electrical components andinstruments shown in FIG. 26 is not shown in order to simplify thedrawing. Furthermore, all power and signal junction boxes are not shownin order to simplify the drawing.

Furthermore, the DAQ device 200 and industrial computer 300 enable thehealth monitoring of Cooling Tower Thermal Capacity, energy consumptionand cooling tower operation as a way to manage energy and therebyfurther enhance cooling performance, troubleshooting and planning foradditional upgrades and modifications.

The Federal Clean Air Act and subsequent legislation will requiremonitoring of emissions from cooling towers of all types (Wet Cooling,Air and HVAC). Air and hazardous gas monitors can be integrated into themotor housing 21 as Line Replaceable Units to sense leaks in the system.The Line Replaceable Units (LRU) are mounted and sealed into the motorin a manner similar to the (LRU) vibration sensors described in theforegoing description. The LRUs will use power and data communicationresources available to other components of the variable process controlsystem. Hazardous gas monitors can also be located at various locationsin the cooling tower fan stack and air-flow stream. Such monitors can beelectronically integrated with DAQ device 200. The monitors provideimproved safety with 100% monitoring of dangerous gases and also providethe capability to trace the source of the gas (e.g. leaking condenser,heat exchanger, etc.). Such a feature can prevent catastrophic events.

In response to the data provided by the sensors, DAQ device 200generates appropriate signals to control operation of motor 20, andhence fan assembly 12. Thus, the variable process control system of thepresent invention employs feedback control of motor 20 and monitors alloperation and performance data in real-time. As a result, the operationof motor 20 and fan assembly 12 will vary in response to changes inoperating conditions, process demand, environmental conditions and thecondition of subsystem components. The continuous monitoring featureprovide by the feedback loops of the variable process control system ofthe present invention, shown in FIG. 3, is critical to efficientoperation of the cooling tower and the prevention of failure of anddamage to the cooling tower and the components of the system of thepresent invention. As a result of continuously monitoring the parametersof motor 20 that directly relate to the tower airflow, operatingrelationships can be determined and monitored for each particularcooling tower design in order to monitor motor health, cooling towerhealth, Cooling Tower Thermal Capacity, provide supervision, triggerinspections and trigger maintenance actions. For example, in the systemof the present invention, the horsepower (HP) of motor 20 is related toairflow across fan 12. Thus, if the fill material of the tower isclogged, the airflow will be reduced. This means that motor 20 and fanassembly 12 must operate longer and under greater strain in order toattain the desired basin temperature. The temperature within theinterior of motor casing 21 and stator 32 increases and the motor RPMstarts to decrease. The aforementioned sensors measure all of theseoperating conditions and provide DAQ device 200 with data thatrepresents these operating conditions. The feedback loops continuouslymonitor system resonant vibrations that occur and vary over time andinitiate operational changes in response to the resonant vibrationsthereby providing adaptive vibration control. If resonant vibrationsoccur at a certain motor speed, then the feedback loops cause thatparticular motor speed (i.e. RPM) to be locked out. When a motor speedis locked out, it means that the motor 20 will not be operated at thatparticular speed. If the vibration signature is relatively high, whichmay indicate changes in the fan blade structure, ice build-up or apotential catastrophic blade failure, the feedback loops will cause thesystem to shut down (i.e. shut down motor 20). If a vibration signaturecorresponds to stored data representing icing conditions (i.e.temperature, wind and fan speed), then DAQ device 200 will automaticallyinitiate the De-Icing Mode of operation. Thus, the feedback loops,sensors, pump status signals, and DAQ device 200 cooperate to:

-   -   a) measure vibrations at the bearings of motor 20;    -   b) measure temperature at the stator of motor 20;    -   c) measure temperature within motor casing 21;    -   d) measure environmental temperatures near motor 20 and fan        assembly 12;    -   e) determine process demand;    -   f) measure the temperature of the water in the cooling tower        collection basin;    -   g) identify high vibrations which are the characteristics of        “blade-out” or equivalent and immediately decelerate the fan to        zero (0) RPM and hold the fan from windmilling, and immediately        alert the operators using the known alert systems (e.g. email,        text or DCS alert);    -   h) lock out particular motor speed (or speeds) that create        resonance;    -   i) identify icing conditions and automatically initiate the        De-Icing Mode of operation and alert operators and personnel via        e-mail, text or DCS alert; and    -   j) route the basin-water temperature data to other portions of        the industrial process so as to provide real-time cooling        feedback information that can be used to make other adjustments        in the overall industrial process.

In a preferred embodiment, the variable process control system of thepresent invention further comprises at least one on-sight camera 480that is located at a predetermined location. Camera 480 is in electricalsignal communication with communication data junction box 111 andoutputs a video signal that is fed to DAQ device 200. The video signalsare then routed to display screens that are being monitored byoperations personnel. In a preferred embodiment, the video signals arerouted to industrial computer 300 and host server 310. The on-sightcamera 480 monitors certain locations of the cooling tower to ensureauthorized operation. For example, the camera can be positioned tomonitor motor 20, the cooling tower, the fan, etc. for unauthorizedentry of persons, deformation of or damage to system components, or toconfirm certain conditions such as icing. In a preferred embodiment,there is a plurality of on-sight cameras.

Industrial computer 300 is in data communication with data base 301 forstoring (1) historical data, (2) operational characteristics ofsubsystems and components, and (3) actual, real-time performance andenvironmental data. Industrial computer 300 is programmed to use thisdata to optimize energy utilization by motor 20 and other systemcomponents, generate trends, predict performance, predict maintenance,and monitor the operational costs and efficiency of the system of thepresent invention. Industrial computer 300 uses historical data, as afunction of date and time, wherein such historical data includes but isnot limited to (1) weather data such as dry bulb temperature, wet bulbtemperature, wind speed and direction, and barometric temperature, (2)cooling tower water inlet temperature from the process (e.g. crackingcrude), (3) cooling tower water outlet temperature return to process,(4) fan speed, (5) cooling tower plenum pressure at fan inlet, (6)vibration at bearings, (7) all motor temperatures, (8) cooling towerwater flow rate and pump flow-rates, (9) basin temperature, (10) processdemand for particular months, seasons and times of day, (11) variationsin process demand for different products, e.g. light crude, heavy crude,etc., (12) previous maintenance events, and (13) library of vibrationsignatures, (14) cooling tower design, (15) fan map, (16) fan pitch and(17) Cooling Tower Thermal Capacity.

Industrial computer 300 also stores the operational characteristics ofsubsystems or components which include (1) fan pitch and balancing atcommissioning, (2) known motor characteristics at commissioning such ascurrent, voltage and RPM ratings, typical performance curves, andeffects of temperature variations on motor performance, (3) variation inperformance of components or subsystem over time or between maintenanceevents, (4) known operating characteristics of variable frequency drive(VFD), (5) operating characteristics of accelerometers includingaccuracy and performance over temperature range, and (6) cooling towerperformance curves and (7) fan speed curve. Actual real-time performanceand environmental data are measured by the sensors of the system of thepresent invention and include:

-   -   1) weather, temperature, humidity, wind speed and wind        direction;    -   2) temperature readings of motor interior, motor casing, basin        liquids, air flow generated by fan, variable frequency drive,        and data acquisition device;    -   3) motor bearing accelerometer output signals representing        particular vibrations (to determine fan pitch, fan balance and        fan integrity);    -   4) plenum pressure at fan inlet;    -   5) pump flow-rates which indicate real-time variations in        process demand;    -   6) motor current (amp) draw and motor voltage;    -   7) motor RPM (fan speed);    -   8) motor torque (fan torque);    -   9) motor power factor;    -   10) motor horsepower, motor power consumption and efficiency;    -   11) exception reporting (trips and alarms);    -   12) system energy consumption; and    -   13) instrumentation health.

Industrial computer 300 processes the actual real-time performance andenvironmental data and then correlates such data to the storedhistorical data and the data representing the operationalcharacteristics of subsystems and components in order to perform thefollowing tasks: (1) recognize new performance trends, (2) determinedeviation from previous trends and design curves and related operatingtolerance band, (3) determine system power consumption and relatedenergy expense, (4) determine system efficiency, (5) development ofproactive and predictive maintenance events, (6) provide information asto how maintenance intervals can be maximized, (7) generate new fanspeed curves for particular scenarios, and (8) highlight areas whereinmanagement and operation can be improved. VFD device 22 provides DAQdevice 200 with data signals representing motor speed, motor current,motor torque, and power factor. DAQ device 200 provides this data toindustrial computer 300. As described in the foregoing description,industrial computer 300 is programmed with design fan map data andcooling tower thermal design data. Thus, for a given thermal load(temperature of water in from process, temperature of water out fromprocess and flow, etc.) and a given day (dry bulb temp, wet bulb temp,barometric pressure, wind speed and direction, etc.), the presentinvention predicts design fan speed from the tower performance curve andthe fan map and then compares the design fan speed to operatingperformance. The design of each tower is unique and therefore theprogramming of each tower is unique. The programming of all towersincludes the operational characteristic that a tower clogged with fillwould require the motor to run faster and longer and would be capturedby trending. Fan inlet pressure sensors are in electronic signalcommunication with DAQ device 200 and provide data representing airflow.Since industrial computer 300 determines operating tolerances based ontrending data, the operation of the fan 12 at higher speeds may triggeran inspection. This is totally contrary to prior art fan drive systemswherein the operators do not know when there are deviations inoperational performance when tower fill becomes clogged.

Industrial computer 300 is programmed to compare the signals of thevibration sensors 400, 402, 404 and 406 on motor the bearing housings 50and 52 as a way to filter environmental noise. In a preferredembodiment, industrial computer 300 is programmed so that certainvibration frequencies are maintained or held for a predetermined amountof time before any reactive measures are taken. Certain vibrationfrequencies indicate different failure modes and require a correspondingreaction measure. The consistent and tight banding of the vibrationsignature of motor 20 allows for greater control and supervision becausechanges in the system of the present invention can be isolated andanalyzed immediately thereby allowing for corrective action. Isolatedvibration spikes in the system of the present invention can be analyzedinstantaneously for amplitude, duration, etc. Opposing motor bearingsignatures can be compared to minimize and eliminate trips due toenvironmental vibrations without impacting safety and operation (falsetrip). As described in the foregoing description, industrial computer300 is also programmed with operational characteristics of thewet-cooling tower and ACHE. For example, industrial computer 300 hasdata stored therein which represents the aerodynamic characteristics ofthe fill material in the cooling tower. The processor of industrialcomputer 300 implements algorithms that generate compensation factorsbased on these aerodynamic characteristics. These compensation factorsare programmed into the operation software for each particular coolingtower. Thus, the positive or negative aerodynamic characteristics of thefill material of a particular wet-cooling tower or ACHE are used inprogramming the operation of each wet-cooling tower or ACHE. Asdescribed in the foregoing description, industrial computer 300 isprogrammed with the historical weather data for the particulargeographical location in which the wet-cooling tower or ACHE is located.Industrial computer 300 is also programmed with historical demand trendwhich provides information that is used in predicting high-processdemand and low-process demand periods. Since industrial computer 300 andDAQ device 200 are programmed with the cooling tower thermal design datathat is unique to each tower including the fan map, each cooling towercan be designed to have its own unique set of logic depending on itsgeographical location, design (e.g. counter-flow, cross flow, ACHE,HVAC) and service (e.g. power plant, refinery, commercial cooling,etc.). When these characteristics are programmed into industrialcomputer 300, these characteristics are combined with sufficientoperational data and trending data to establish an operational curvetolerance band for that particular cooling tower. This enables coolingtower operators to predict demand based upon historical operationalcharacteristics and optimize the fan for energy savings by using subtlespeed changes as opposed to dramatic speed changes to save energy.

A significant feature of the present invention is that the air flowthrough the cooling tower is controlled via the variable speed fan tomeet thermal demand and optimize energy efficiency of the system. DAQdevice 200 generates motor-speed control signals that are based onseveral factors including cooling tower basin temperature, historicaltrending of weather conditions, process cooling demand, time of day,current weather conditions such as temperature and relative humidity,cooling tower velocity requirements, prevention of icing of the tower byreducing fan speed, and de-icing of the tower using reverse rotation ofthe fan. Thus, the system of the present invention can anticipatecooling demand and schedule the fan (or fans) to optimize energy savings(ramp up or ramp down) while meeting thermal demand. The system of thepresent invention is adaptive and thus learns the cooling demand byhistorical trending (as a function of date and time).

The speed of the fan or fans may be increased or decreased as a resultof any one of several factors. For example, the speed of the fan or fansmay be decreased or increased depending upon signals provided by thebasin water temperature sensor. In another example, the speed of the fanor fans may be increased or decreased as a result of variable processdemand wherein the operator or programmable Distributed Control System(DCS) 315 generates a signal indicating process-specific cooling needssuch as the need for more cooling to maintain or lower turbinebackpressure. In a further example, the speed of the fan or fans may beincreased or decreased by raising the basin temperature if the plant isoperating at part-load production. Fan speed can also be raised in“compensation mode” if a cell is lost in a multiple-cell tower in orderto overcome the cooling loss. Since motor 20 provides more torque than acomparable prior art induction motor, motor 20 can operate withincreased fan pitch providing required design airflow at slower speeds.Since most 100% speed applications operate at the maximum fan speed of12,000 fpm to 14,000 fpm maximum tip speed depending upon the fandesign, the lower speeds of motor 20 provide an airflow buffer that canbe used for hot day production, compensation mode and future coolingperformance.

A particular geographical location may have very hot summers and verycold winters. In such a case, the variable process control systemoperates the fan in the “hot-day” mode of operation on very hot summerdays in order to meet the maximum thermal load at 100%. When the maximumthermal load diminishes, the speed of the fan is then optimized at lowerfan speeds for energy optimization. The fan will operate in this energyoptimization mode during the cooler months in order to optimize energyconsumption, which may include turning fan cells off. Since the torqueof motor 20 is constant, the shifting of fan speed between maximumoperation and energy optimization is without regard to fan pitch. Theconstant, high-torque characteristics of motor 20 allow the fan to bere-tasked for (true) variable speed duty. Thus, the variable processcontrol system of the present invention operates in a manner totallyopposite to that of prior art fan drive systems wherein an inductionmotor drives the fan at 100% speed, typically between 12,000 and 14,000ft/min tip speed, and wherein the fan remains at constant speed and itspitch is limited by the torque limitations of the induction motor. Inorder to provide the required torque, the size of the prior artinduction motor would have to be significantly increased, but this woulddramatically increase the weight of the motor. On the other hand, in thepresent invention, permanent magnet motor 20 is able to drive the fan atslower speeds with increased fan pitch without exceeding the fan tipspeed limitation of 12,000 feet/minute. Slower fan speed also allows forquieter operation since fan noise is a direct function of speed. Motor20 allows 100% design air flow to be set below the maximum fan tipspeed. This feature allows for a design buffer to be built into thevariable process control system of the present invention to allow foradditional cooling capacity in emergency situations such as thecompensation mode (for multi-cell systems) or extremely hot days or forincreased process demand such as cracking heavier crude. The constanttorque of motor 20 also means that part-load operation is possiblewithout the limitations and drawbacks of prior art fan drive systemsthat use a gearbox and induction motor. In such prior art systems,part-load torque may not be sufficient to return the fan to 100% speedand would typically require a larger induction motor with increasedpart-load torque.

Motor 20 converts relatively more “amperes to air” than prior artgearbox systems. Specifically, during actual comparison testing of acooling system using motor 20 and a cooling system using a prior artgearbox system, motor 20 is at least 10% more efficient than prior artgearbox systems. During testing, at 100% fan speed and design pitch, apower-sight meter indicated the prior art gearbox system demanded 50 kWwhereas motor 20 demanded 45 kW. Almost all existing towers are coolinglimited. Since motor 20 is a drop-in replacement for prior artgearboxes, motor 20 will have an immediate impact on cooling performanceand production.

The system and method of the present invention is applicable tomulti-cell cooling apparatuses. For example, a wet-cooling tower maycomprise a plurality of cells wherein each cell has a fan, fan stack,etc. Similarly, a multi-cell cooling apparatus may also comprise aplurality of ACHEs, HVACs or chillers (wet or dry, regardless ofmounting arrangement). Referring to FIGS. 15A, 15B and 15C, there ismulti-cell cooling apparatus 600 which utilizes the variable processcontrol system of the present invention. Multi-cell cooling apparatus600 comprises a plurality of cells 602. Each cell 602 comprises fanassembly 12 and fan stack 14. Fan assembly 12 operates within fan stack14 as described in the foregoing description. Each cell 602 furthercomprises load bearing permanent magnet motor 20. In this embodiment,the system of the present invention includes Motor Control Center (MCC)630. A Motor Control Center (MCC) typically serves more than motor orfan cell. The Motor Control Center is typically located outside of theClass One, Division Two area on the ground, at least ten feet from thecooling tower. The Motor Control Center is in a walk-in structure thathouses VFD device 22, DAQ device 200, industrial computer 300, powerelectronics and Switchgear. The Motor Control Center is air-conditionedto cool the electronics. The Motor Control Center is typically a walk-inmetal building that houses the DAQ device, the Variable FrequencyDrives, the industrial computer 300 and the power electronics. MCC 630comprises a plurality of Variable Frequency Drive (VFD) devices 650.Each VFD device 650 functions in the same manner as VFD device 22described in the forgoing description. Each VFD device 650 controls acorresponding motor 20. Thus, each motor 20 is controlled individuallyand independent of the other motors 20 in the multi-cell coolingapparatus 600. MCC 630 further comprises a single Data Acquisition (DAQ)device 660 which is in data signal communication with all of the VFDdevices 650 and all sensors (e.g. motor, temperature, vibration,pump-flow, etc.) in each cell. These sensors were previously describedin the foregoing description. DAQ device 660 controls the VFD devices650 in the same manner as DAQ device 200 controls VFD device 22 whichwas previously described in the foregoing description. DAQ device 660 isalso in data signal communication with industrial computer 300 via databus 670. Industrial computer 300 is in data signal communication withdatabase 301. Both industrial computer 300 and database 301 werepreviously described in the foregoing description. As shown in FIG. 15A,there are a plurality of communication data junction boxes 634 whichreceive the signals outputted by the sensors (e.g. temperature,pressure, vibration). Each communication data junction box 634 is indata signal communication with DAQ device 660. Each communication datajunction box 634 has the same function and purpose as communication datajunction box 111 described in the foregoing description. The powersignals outputted by the VFD devices 650 are routed to motor disconnectjunction boxes 636 which are located outside of fan stack 14. Each motordisconnect junction box 636 has the same configuration, purpose andfunction as motor disconnect junction box 106 previously described inthe foregoing description. Since there is a dedicated VFD device 650 foreach motor 20, each cell 602 is operated independently from the othercells 602. Thus, this embodiment of the present invention is configuredto provide individual and autonomous control of each cell 602. Thismeans that DAQ device 660 can operate each fan at different variablespeeds at part-load based on process demand, demand trend, air-flowcharacteristics of each tower (or fill material) and environmentalstress. Such operation optimizes energy savings while meeting variablethermal loading. Such a configuration improves energy efficiency andcooling performance. For example, if all fans are operating at minimumspeed, typically 80%, and process demand is low, DAQ device 660 isprogrammed to output signals to one or more VFD devices 650 to shut offthe corresponding fans 12. DAQ device 660 implements a compensation modeof operation if one of the cells 602 is not capable of maximumoperation, or malfunctions or is taken off line. Specifically, if onecell 602 is lost through malfunction or damage or taken off line, DAQdevice 660 controls the remaining cells 602 so these cells compensatefor the loss of cooling resulting from the loss of that cell. End wallcells are not as effective as cells in the middle of the tower andtherefore, the end wall cells may be shut off earlier in hot weather ormay need to run longer in cold weather. In accordance with theinvention, the fan speed of each cell 602 increases and decreasesthroughout the course of a cooling day in a pattern generally similar toa sine wave as shown in FIG. 9. DAQ device 660 can be programmed so thatwhen the basin temperature set-point is not met (in the case of awet-cooling tower), DAQ device 660 issues signals to the VFD devices 650to increase fan speed based on a predictive schedule of speed incrementsbased on (a) part-load based on process demand, (b) demand trend, (c)air flow characteristics of each tower (or fill material) and (d)environmental stress without returning fan speed to 100%. Thisoperational scheme reduces energy consumption by the cell and preservesthe operational life of the equipment. This is contrary to prior artreactive cooling schedules which quickly increase the fans to 100% fanspeed if the basin temperature set-point is not met.

The system and method of the present invention provides infinitevariable fan speed based on thermal load, process demand, historicaltrending, energy optimization schedules, and environmental conditions(e.g. weather, geographical location, time of day, time of year, etc.).The present invention provides supervisory control based on continuousmonitoring of vibrations, temperature, pump flow rate and motor speed.The present invention uses historical trending data to execute currentfan operation and predicting future fan operation and maintenance. Thesystem provides automatic de-icing of the fan without input from theoperator.

De-icing cooling towers using load bearing permanent magnet motor 20 isrelatively easier, safer and less expensive than de-icing cooling towersusing prior art gearbox fan drive systems. The capability of motor 20 tooperate the fans at slower speeds in colder weather reduces icing. Motor20 has no restrictions or limitations in reverse rotation and cantherefore provide the heat retention required to de-ice a tower inwinter. DAQ device 200 is configured to program the operation of motor20 to implement de-icing based on outside temperature, wind speed anddirection, wet bulb temperature, and cooling tower inlet/outlet and flowrate. All parameters are used to develop a program of operation that istailored made for the particular and unique characteristics of eachcooling tower, the cooling tower's location and environment stress.

Motor 20 provides constant high torque thereby allowing the fan tooperate at a relatively slower speed with greater pitch to satisfyrequired air-flow while reducing acoustic noise (acoustic noise is afunction of fan speed) with additional airflow built into the system forother functions. This is not possible with prior art fan drive systemsthat use a single-speed gear-box and induction motor that drives the fanat 100% speed at the maximum tower thermal condition for 100% of thetime. Unlike prior art fan drive systems, motor 20 is capable ofinfinite variable speed in both directions. Motor 20 is configured toprovide infinite variable speed up to 100% speed with constant torquebut without the duration restrictions of prior art fan drive systemsthat relate to induction motor torque at part-load, drive trainresonance, torque load relative to pitch, and induction motor coolingrestrictions.

The infinite variable speed of motor 20 in both directions allows thefan to match the thermal loading to the environmental stress. This meansmore air for hot-day cooling and less air to reduce tower icing. Theinfinite variable speed in reverse without duration limitations enablesde-icing of the tower. Motor 20 provides high, constant torque in bothdirections and high, constant torque adjustment which allows for greaterfan pitch at slower fan speeds. These important features allow for abuilt-in fan-speed buffer for emergency power and greater variation indiurnal environments and seasonal changes without re-pitching the fan.Thus, the infinite variable speed adjustment aspect of the presentinvention allows for built-in cooling expansion (greater flow) andbuilt-in expansion without changing a motor and gear box as required inprior art fan drive systems. The present invention provides unrestrictedvariable speed service in either direction to meet ever changingenvironmental stress and process demand that results in improvedcooling, safety and reduced overhead. All parameters are used to developa unique programmed, operation for each cooling tower design, thecooling tower's geographical location and the correspondingenvironmental stress. DAQ device 200 operates motor 20 (and thus fan 12)in a part-load mode of operation that provides cooling with energyoptimization and then automatically shifts operation to a full-load modethat provides relatively more variable process control which is requiredto crack heavier crude. Once the process demand decreases, DAQ device200 shifts operation of motor 20 back to part-load.

Due to the fan hub interface, the motor shaft 24 is relatively large.The bearings of motor 20 are relatively large in order to accommodatethe relatively large motor shaft 24. Combined with the slow speed of theapplication, the bearing system is only 20% loaded, thereby providing anL10 life of 875,000 hours. The 20% loading and unique bearing design ofmotor 20 provides high fidelity of vibration signatures and consistentnarrow vibration band signatures well below the current trip settingvalues. As a result, there is improved monitoring via historicaltrending and improved health monitoring via vibration signatures beyondthe operating tolerance. The bearing system of motor 20 enables motor 20to rotate fans of different diameters and at all speeds and torques inboth directions and is specifically designed to bear radial and yawloads from the fan, axial loads in both directions from fan thrust andfan dead weight, and reverse loads which depend upon the mountingorientation of motor 20, e.g. motor shaft up, motor shaft down, motorshaft in horizontal orientation, or combinations thereof.

The variable process control system of the present invention determinesCooling Tower Thermal Capacity so as to enable operators to identifyproactive service, maintenance and cooling improvements and expansions.The present invention provides the ability to monitor, control,supervise and automate the cooling tower subsystems so as to manageperformance and improve safety and longevity of these subsystems. Thesystem of the present invention is integrated directly into an existingrefinery Distributed Control System (DCS) so as to allow operators tomonitor, modify, update and override the variable process control systemin real time. Operators can use the plant DCS 315 to send data signalsto the variable process control system of the present invention toautomatically increase cooling for cracking crude or to preventauxiliary system fouling or any other process. As shown by the foregoingdescription, for a given fan performance curve, a cooling tower can beoperated to provide maximum cooling as a function of fan pitch andspeed. Fan speed can be reduced if basin temperature set-point is met.The present invention provides accurate cooling control with variablespeed motor 20 as a function of environmental stress (e.g. cooling andicing), variable process control (i.e. part load or more cooling forcracking crude, etc.) and product quality such as light end recoverywith more air-per-amp for existing installations. The variable processcontrol system of the present invention allows operators to monitorcooling performance in real time thereby providing the opportunity toimprove splits and production and identify service and maintenancerequirements to maintain cooling performance and production throughput.Furthermore, the data acquired by the system of the present invention isutilized to trend cooling performance of the cooling tower which resultsin predictive maintenance that can be planned before outages occur asopposed to reactive maintenance that results in downtime and loss ofproduction. The unique dual-bearing design of motor 20, the placement ofaccelerometers, velocity probes and displacement probes on each of thesebearings, and the vibration analysis algorithms implemented byindustrial computer 300 allow significant improvements in fan vibrationmonitoring and provides an effective trim balancing system to remove thefan dynamic couple. The trim balance feature removes the fan dynamiccouple which reduces structural fatigue on the cooling tower.

The present invention eliminates many components and machinery used inprior art fan drive systems such as gearboxes, shafts and couplings,two-speed motors, gearbox sprag clutches to prevent reverse operation,electric and gerotor lube pumps for gearboxes and vibration cut-offswitches. Consequently, the present invention also eliminates themaintenance procedures related to the aforesaid prior art components,e.g. pre-seasonal re-pitching, oil changes and related maintenance. Thepresent invention allows monitoring and automation of the operation ofthe cooling tower subsystems to enable management of performance andimprovement in component longevity. The present invention allowscontinuous monitoring and management of the permanent magnet motor 20,the fan and the cooling tower itself. The present invention allows forrapid replacement of a prior art fan drive system with motor 20, withoutspecialized craft labor, for mission critical industries minimizingproduction loss. The system of the present invention provides anautonomous de-icing function to de-ice and/or prevent icing of thecooling tower.

The system of the present invention is significantly more reliable thanprior art systems because the present invention eliminates manycomponents, corresponding complexities and problems related to prior artsystems. For example, prior art gearboxes and corresponding drive trainsare not designed for the harsh environment of cooling towers but wereinitially attractive because of their relatively lower initial cost.However, in the long run, these prior art fan drive systems haveresulted in high Life-Cycle costs due to continuous maintenance andservice expense (e.g. oil changes, shaft alignments, etc.), equipmentfailure (across-the-line start damage), application of heavy dutycomponents, poor reliability, lost production and high energyconsumption.

The data collected by DAQ device 200, which includes motor voltage,current, power factor, horsepower and time is used to calculate energyconsumption. In addition, voltage and current instrumentation areapplied to the system to measure energy consumption. The energyconsumption data can be used in corporate energy management programs tomonitor off-performance operation of a cooling tower. The energyconsumption data can also be used to identify rebates from energysavings or to apply for utility rebates, or to determine carbon creditsbased upon energy savings. The system of the present invention alsogenerates timely reports for corporate energy coordinators on a scheduleor upon demand. The data provided by DAQ device 200 and thepost-processing of such data by industrial computer 300 enables coolingperformance management of the entire system whether it be a wet-coolingtower, air-cooled heat exchanger (ACHE), HVAC systems, chillers, etc.Specifically, the data and reports generated by DAQ device 200 andindustrial computer 300 enable operators to monitor energy consumptionand cooling performance. The aforesaid data and reports also provideinformation as to predictive maintenance (i.e. when maintenance ofcooling tower components will be required) and proactive maintenance(i.e. maintenance to prevent a possible breakdown). Industrial computer300 records data pertaining to fan energy consumption and thus,generates fan energy consumption trends. Industrial computer 300executes computer programs and algorithms that compare the performanceof the cooling tower to the energy consumption of the cooling tower inorder to provide a cost analysis of the cooling tower. This is animportant feature since an end user spends more money operating a poorperforming tower (i.e. lower flow means more fan energy consumption andproduction loss) than a tower than is in proper operating condition.Industrial computer 300 implements an algorithm to express the fanenergy consumption as a function of the tower performance which can beused in annual energy analysis reports by engineers and energy analyststo determine if the tower is being properly maintained and operated.Energy analysis reports can be used to achieve energy rebates fromutilities and for making operational improvement analysis, etc. Withrespect to large capital asset planning and utilization cost, a relationis derived by the following formula:N=(Cooling Tower Thermal Capacity)/(Cooling Tower Energy Consumption)wherein the quotient “N” represents a relative number that can be usedto determine if a cooling tower is operating properly or if it hasdeteriorated or if it is being incorrectly operated. Deterioration andincorrect operation of the cooling tower can lead to safety issues suchas catastrophic failure, poor cooling performance, excessive energyconsumption, poor efficiency and reduced production.

The present invention provides accurate cooling control with variablespeed motor 20 as a function of environmental stress (cooling andicing), variable process control (part load or more cooling forcracking, etc.) and product quality such as light end recovery with moreair-per-amp for existing installations. The present invention alsoprovides automatic adjustment of fan speed as a function of coolingdemand (process loading), environmental stress and energy efficiency andprovides adaptive vibration monitoring of the fan to prevent failure dueto fan imbalance and system resonance. The present invention allows thefans to be infinitely pitched due to constant, high torque. The built-invibration monitoring system provides a simple and cost effective trimbalance to eliminate fan dynamic couple and subsequent structural wearand tear. The variable process control system of the present inventionreduces maintenance to auxiliary equipment, maintains proper turbineback pressure and prevents fouling of the condensers. Motor 20 providesconstant torque that drives the fan at lower speed to achieve designairflow at a greater fan pitch thereby reducing fan noise whichtypically increases at higher fan speeds (noise is a function of fanspeed).

The present invention reduces energy consumption and does not contributeto global warming. The high-torque, variable speed, load bearingpermanent magnet motor 20 expands the operational range of the fan tomeet ever changing process load changes and environmental conditions byproviding high, constant torque for full fan pitch capability. Thisenables increased airflow for existing installations, providesunrestricted variable speed for energy savings and reduction of iceformation, and allows reverse operation of the fan for retaining heat inthe cooling tower for de-icing.

Although the previous description describes how motor 20 and thecorresponding system components (e.g. VFD 22, DAQ device 200, etc.) maybe used to retrofit an existing cooling tower that used a prior art fandrive system, it is to be understood that the direct-drive system andvariable process control system of the present invention can be used innewly constructed cooling towers, regardless of the materials used toconstruct such new cooling towers, e.g. wood, steel, concrete piermountings, pultruded fiber-reinforced plastic (FRP) structures, orcombinations thereof.

In an alternate embodiment of the invention, the load bearing motor 20is used to drive fans that are supported by a separate, independentstructure. Specifically, in such an embodiment, the axial yaw and mostradial loads are supported by the separate, independent structure andthe load bearing motor provides torque, speed and some radial loading.

Referring to FIG. 27, there is shown another wet cooling tower thatutilizes load bearing, direct drive motor 20 and the variable processcontrol system of the present invention. Wet cooling tower 1800comprises a cooling tower structure 1802 which includes generallyvertical walls 1804, 1805, 1806 and a forth, front wall that is notshown, that form a duct. Wet cooling tower 1800 further comprises topstructure 1808. Motor 20 is attached to top structure 1808 and isoriented such that motor shaft 24 extends downward. Fan 12 is attachedto motor shaft 24. Wet cooling tower structure 1800 includes waterdistribution device 1820, fill material or fill pack 1830 and collectionbasin 1840. Collection basin 1840 collects fluids 1850 (e.g. water).Since such cooling tower structures are known in the art, the details ofair-flow and water flow are not discussed herein. In an alternateembodiment, motor 20 is attached to top structure 1808 and is orientedsuch that motor shaft 24 extends upward and fan 12 is attached to motorshaft 24. In such an embodiment, fan 12 is above motor 20.

Referring to FIG. 28, there is shown a diagram of one type of hybridcooling tower that utilizes the load bearing motor 20 and the variableprocess control system of the present invention. Hybrid cooling tower2000 comprises cooling tower structure 2002 which has interior 2003.Cooling tower structure 2002 comprises fan stack 2004 that is positionedat the upper portion of cooling tower structure 2002. Load bearing motor20 is supported by horizontal member 2006. Fan 12 is connected to shaft24 of load bearing motor 20. Hybrid cooling tower 2000 further comprisestube bundle or tube network 2010 that is positioned beneath the fan 12.Hot fluid or hot water 2012 coming from the process is inputted intotube bundle 2010. Cold water 2014 exits tube bundle 2010. Hybrid coolingtower 2000 further comprises water distribution device 2020 and wettower fill material or fill pack 2030. Fill material 2030 is positionedunder water distribution device 2020. Water distribution device 2020distributes hot fluid or water 2012 over water tower fill material 2030.Hybrid cooling tower 2000 further comprises collection basin 2040 whichcollects the cooled fluid and outputs cooling water 2050. Cooling water2050 is returned to the process. Air 2060 is allowed to flow intointerior 2003 via air inlet device 2070. Typically, air inlet device2070 is configured as a shutter device. The rotation of fan 12 createsan air flow, indicated by reference numbers 3000, which flows upward andout through fan stack 2004. In some types of hybrid cooling towers, mistelimination devices are used to eliminate mist carried by the air flowfrom wet tower fill material 2030.

The present invention is also applicable to steel mills and glassprocessing, as well as any other process wherein the control of coolingwater is critical. Temperature control of the water is crucial forcooling the steel and glass product to obtain the correct materialcomposition. The capability of the present invention to provide constantbasin water temperature is directly applicable to steel mill operation,glass processing and resulting product quality and capacity. Thecapability of motor 20 and fan 12 to operate in reverse withoutlimitation allows more heat to be retained in the process water on colddays. This would be accomplished by slowing the fan 12 or operating thefan 12 in reverse in order to retain more heat in the tower and thus,more heat in the process water in the basin. The variable processcontrol feature of the system of the present invention can deliverinfinite temperature variation on demand to the process as required tosupport production and improve control and quality of the product.

It is to be understood that the direct-drive fan system of the presentinvention may be configured with motors or prime drivers other than thepermanent magnet motor described in the forgoing description. Forexample, in one alternate embodiment, permanent magnet motor 20 and thepermanent magnet motors in variable speed pumps 1722, 1730, 1738 and1752 are replaced by synchronous reluctance motors. In such anembodiment, the synchronous reluctance motor that rotates the fancomprises a casing, stator, rotor, shaft, bearing system and sealingsystem that are designed to support the fan loads (discussed in theforegoing description) with respect to operating temperature, operatingspeed, orientation and motor design characteristics. In one embodiment,the synchronous reluctance motor that rotates the fan comprises the samebearing configuration as the load bearing permanent magnet motor thatwas discussed in the foregoing description. Thus, the modified loadbearing synchronous reluctance motor would be configured to bear all fanloads whether the fan is rotating in forward, reverse or is at 0.00 RPMand also bear all loads created by external forces exerted on the fan,such as relatively strong wind gusts. In such an embodiment, theVariable Process Control system of the present invention controls thesynchronous reluctance motors in the same manner as was done for thepermanent magnet motors.

Motor 20 and the motors of the variable speed pumps 1722, 1730, 1738 and1752 may be realized by other suitable load bearing motors. For example,the load bearing direct drive system of the present invention maycomprise any of the motor types listed below that are designed inaccordance with the invention such that the motor comprises a casing,stator, rotor, shaft, bearing system and sealing system that support thefan loads (discussed in the foregoing description) with respect tooperating temperature, operating speed, orientation and motor designcharacteristics. These motor types include:

-   -   a) single speed Totally Enclosed Fan Cooled (TEFC) AC induction        motor (e.g. asynchronous motor);    -   b) variable speed TEFC AC induction motor;    -   c) inverted rated induction motor with VFD;    -   d) switched reluctance motor;    -   e) brushless DC motor;    -   f) pancake DC motor;    -   g) synchronous AC motor;    -   h) salient pole interior permanent magnet motor;    -   i) interior permanent magnet motor;    -   j) finned laminated, permanent magnet motor;    -   k) series-wound motor or universal motor;    -   l) traction motor;    -   m) series-wound, brushed DC motor; and    -   n) stepper motor.

It is to be understood that the casing, stator, rotor, shaft, bearingsystem and sealing system of the motor may be designed to have differentsizes or dimensions in order to provide a desired torque and speed rangefor a particular fan in a cooling tower or ACHE tower.

The present invention may be applied to applications other than coolingtowers, air-cooled heat exchangers or hybrid cooling towers. Forexample, all of the embodiments of the direct-drive system and variableprocess control system of the present invention may be used in otherapplications including HVAC, chillers, windmills or wind turbinegenerators, paper machines, marine propulsion systems, ski-lifts andelevators. The present invention is also applicable to steel mills andglass processing, as well as any other process wherein the control ofthe temperature and flow of cooling water is critical. Temperaturecontrol of the water is crucial for cooling the steel and glass productto obtain the correct material composition. The capability of thepresent invention to provide constant basin water temperature isdirectly applicable to steel mill operation, glass processing andresulting product quality and capacity. The capability of thedirect-drive system of the present invention and the fan to operate inreverse without limitation allows more heat to be retained in theprocess water on cold days. This would be accomplished by slowing thefan 12 or operating the fan 12 in reverse in order to retain more heatin the tower and thus, more heat in the process water in the basin. Thevariable process control system of the present invention can deliverinfinite temperature variation on demand to the process as required tosupport production and improve control and quality of the product.

Air-Handling System for Heating, Ventilation and Air-Conditioning (HVAC)

Office buildings, computer data centers, sport complexes, shopping mallsand skyscrapers are investing in Intelligent Building Systems thatactively manage and monitor the buildings for heating, cooling andhumidity during changing weather conditions. A properly operating HVACsystem is paramount in maintaining the health, safety and comfort of abuilding's occupants as well as maintaining and protecting thebuilding's integrity and equipment within the building.

Accordingly, another aspect of the present invention is directed to anair-handling system which may be utilized in a HVAC system. Theair-handling system comprises at least one direct-drive fan system thatcomprises a load bearing, variable speed motor and a relativelylarge-diameter fan that is connected to the rotational shaft of themotor. The air-handling system moves and balances air-flow through theHVAC system. The load bearing, variable speed motor rotates the fan atrelatively slow rotational speeds in order to facilitate balancing theHVAC system during dynamic weather conditions, provide energy savingsand improve noise attenuation. The air-handling system uses motorinformation for feedback to balance the thermal system in less timethereby improving comfort and reducing energy consumption. Theair-handling system also eliminates or substantially minimizes systemlead and lag with variable motor speed and a variable process controlsystem that is adaptive and which learns the process cooling demand byhistorical trending as a function of date and time. The air-handlingsystem uses feedback control loops, similar to the feedback controlloops shown in FIG. 3 and previously described herein. The air-handlingsystem of the present invention can be integrated with existing buildingsensors, thermostats and other electronic circuitry to allow the HVACsystem to anticipate thermal requirements based on trending, demand,weather station data and weather forecast data.

Referring to FIG. 29, there is shown a commercial HVAC system 3100 thatcomprises a direct-drive air handling system 3150 in accordance with oneembodiment of the invention. Air-handling system 3150 comprises a loadbearing, variable speed motor 20 which has been described in theforegoing description and shown in FIGS. 5A and 5B. Motor 20 includesthe vibration and motor-heat sensors that were previously described inthe foregoing description and shown in FIG. 4. The aforesaid vibrationsensors sense the vibrations caused by the rotation of the fan andoutput signals that represent the sensed vibrations. The motor-heatsensors sense the heat within the interior of the motor and the heat ofthe motor stator and output signals that represent the measured orsensed heat. Motor 20 directly controls the speed and torque of the fanfrom one (1.0) RPM. A relatively large, diameter fan 3152 has a fan hub3154 that is directly connected to rotational shaft 24 of motor 20. Inanother embodiment, the fan 3152 is a one-piece fan assembly such as awide chord fan with an integral hub or fan hub system. However, it is tobe understood that motor 20 may be used with any one of a variety offans. Fan 3152 operates within fan stack or ring 3160. Fan stack 3160 isattached to fan deck 3170. Fan 3152 operates within fan stack or fanring 3160 in order to provide the proper fan-head to the particularapplication. In other embodiments, such as relatively large commercialceiling fans, a fan stack or ring is not used. Motor 20 rotates fan 3152at a relatively slow speed. All modes of operation discussed in theforegoing description, such as Soft Start and Soft Stop, can beimplemented by the direct-drive air handling system of the presentinvention. The plenum volume 3172 is below the fan deck 3170. Rotationof fan 3152 moves air through a bank of condenser coils 3174. The plenumvolume 3172 also allows a single axial fan to serve any shape array ofcondenser coils. Motor 20 can be oriented so that motor shaft 24 iseither substantially vertical or substantially horizontal therebyallowing motor 20 to be used in a variety of applications, such asexhaust and furnace blowers, mechanical mixers, chillers, evaporatorsand pumps.

Direct-drive air handling system 3150 (a) improves wetted area or airflow around the condenser coils 3174 and provides improved thermalmanagement, (b) attenuates noise as a result of slower speed fan andprogrammed Soft Start and Soft Stop modes of operation, (c) providesvariable process control and energy savings, (d) allows for reverseoperation of the fan for exhaust back pressure control and de-ice mode(e) can be used with a relatively smaller condenser array therebyreducing weight, (f) uses relatively less space of the installationenvelope and promotes round duct work which improves airflow, and (g)improves reliability, service and maintenance with a single fan that hasone moving part. Fan 3152 is supported solely by the load bearing,variable speed motor 20. As shown in FIGS. 5A and 5B, motor 20 has abearing system that enables the motor 20 to support and bear the fanloads while simultaneously maintaining a critical rotor-to-stator gap.The critical rotor-to-stator gap ensures that proper motor flux isgenerated in order to allow motor 20 to provide the required rotationalspeed and high torque. A variable frequency drive (VFD) device can beused to operate motor 20 as a low, variable speed motor that provideshigh torque even at the low RPM of 1.0 RPM. Operating motor 20 with aVFD allows for controlled starts, controlled stops and windmillingthereby reducing mechanical failures.

In other embodiments, an adjustable speed device (ASD) or variable speeddevice (VSD) is used in place of a variable frequency drive (VFD)device. In an alternate embodiment, motor 20 is operated at a singlespeed. In such an alternate embodiment, a VFD, ASD or VSD is notutilized.

FIG. 30A shows a commercial HVAC system 3200 in accordance with anotherembodiment of the invention. HVAC system 3200 comprises direct-driveair-handling system 3150 shown in FIG. 29 with the addition of adown-stream, direct-drive centrifugal blower 3250. FIG. 30B shows a topview of wide chord fan 3152. As shown in FIGS. 31A and 31B, centrifugalblower 3250 comprises a cantilever fan 3252 that is supported solely byload bearing motor 20. Such a configuration is referred to herein as asingle cantilevered bearing system. The single cantilevered bearingsystem allows motor 20 to be integrated into the centrifugal fan 3252 soas to minimize installation envelope and the width of the centrifugalblower 3250. Centrifugal fan 3252 comprises fan hub 3254 which isconnected to shaft 24 of motor 20. Motor 20 and fan 3252 are positionedwithin the interior of housing 3256. Motor 20 is connected to section3258 of housing 3256.

An alternate embodiment of the system shown in FIG. 31B is configuredwith an “inside-out motor”. In such an embodiment, the motor rotatableshaft is connected to the centrifugal fan but the rotatable shaft doesnot rotate the fan. Instead, the motor housing and stator are integralwith the centrifugal fan to form one integral structure which rotatesabout the motor shaft.

In another embodiment, the centrifugal blower 3250 is configured so thatmotor 20 is positioned outside of plenum 3172.

An alternate embodiment of the centrifugal blower 3250 is shown in FIG.32 as centrifugal blower 3260. Centrifugal blower 3260 comprises housing3261 and a load bearing, permanent magnet motor 3264 that issubstantially the same in construction as motor 20 except motor 3264 hasa substantially longer rotatable shaft 3266. Centrifugal blower 3260comprises centrifugal fan 3268 which is supported by a dual bearingsystem. This dual bearing system comprises the bearing system of motor3264 and a second bearing 3270 that is mounted to housing 3261 andpositioned at end 3272 of shaft 3266.

In another embodiment, centrifugal blower 3260 is configured so thatmotor 3264 is positioned outside of plenum 3172.

Referring to FIG. 33, there is shown a commercial HVAC system 3500 thatcomprises housing 3501, the first direct-drive air-handling system 3150,originally shown in FIG. 29, and second direct-drive air handling system3504. Second air-handling system 3504 is a down-stream, direct-driveaxial fan that comprises fan 3510 and load bearing permanent magnetmotor 20. Fan 3510 comprises fan hub 3512 which is connected to shaft 24of motor 20. Fan 3510 can be configured as any type of fan as requiredto move air at various points through the air-handling system. Forexample, there can be different motor-fan combinations in the sameair-handling system. In one embodiment, fan 3510 is a wide chord fan. Asis known in the art, wide chord fans are configured to move largevolumes of air at relatively low fan speed. Air handling systems 3150and 3504 cooperate to move and balance air in the commercial HVACsystem. Using second air-handling system 3504 instead of a prior artcentrifugal blower results in a relatively shorter installation packagewith less weight and allows the air-handling duct to have a round shapeinstead of a rectangular shape, which complements the circumference ofthe fan for required sealing and improved air-flow through the ductwork. Furthermore, using air-handling system 3504 instead of a prior artcentrifugal blower eliminates lead and lag thereby improving coolingperformance and reducing energy consumption. Using air-handling system3504 also allows for variable process control with feedback andsupervision because fan 3510 is directly driven by motor 20. Motor 20 isconfigured so that fan 3510 can rotate in forward or reverse directions.In one embodiment, a separate variable frequency drive device (VFD) isused with each motor 20 of air-handling systems 3150 and 3504 in orderto rotate the fans in forward or reverse or bring the fans to idle.Using the VFDs also allow implementation of the Soft Start and Soft Stopmodes of operation which were discussed in the foregoing description.Another important advantage is that air-handling system 3504 can eithereliminate or be combined with a prior art centrifugal blower positionedat the end of an HVAC system to maintain system backpressure.

In some embodiments, variable speed devices (VSD) or adjustable speeddevices (ASD) are used to control each motor 20 of the air-handlingsystems 3150 and 3504.

Referring to FIG. 34, there is shown a block diagram of direct-drive airhandling system 3600 and corresponding variable process control system3620 in accordance with another embodiment of the present invention.Air-handling system 3600 comprises a load bearing, electricallycommutated motor (ECM) 3602. The motor 3602 comprises a stator, rotor,rotatable shaft 3604 and integrated motor controller 3606. Fan 3608 isconnected to shaft 3604. In one embodiment, motor controller 3606includes a microprocessor that regulates speed and torque therebyalleviating the need for a separate feedback device. Motor controller3606 is integrated into ECM 3602 and includes an inverter that providespower signals and motor control signals in a manner similar to avariable frequency device (VFD). In one embodiment, ECM 3602 is apermanent magnet motor. In another embodiment, ECM 3602 is a switchedreluctance motor. In a further embodiment, ECM 3602 is an inductionmotor. The ECM 3602 further includes vibration sensors that sense thevibrations of the fan and function in the same manner as the vibrationsensors of motor 20 as shown in FIG. 4. The ECM 3602 further includestemperature sensors that sense the temperature of the motor interior andthe heat of the stator and function in the same manner as the heat andtemperature sensors of motor 20 as shown in FIG. 4. The control system3620 comprises digital acquisition device (DAQ) 3624, industrialcomputer 3626 and a distributed control system (DCS) 3628. The purposeand function of distributed control systems was explained in theforegoing description (see DCS 315 in FIG. 2). In some embodiments, theDCS 3628 may be an existing building management system. Bi-directionalelectronic data signal bus 3630 is in electronic signal communicationwith integrated motor controller 3606 and DAQ 3624. Bi-directionalelectronic data signal bus 3631 is in electronic signal communicationwith DAQ 3624 and industrial computer 3626. Control system 3620 furtherincludes a bi-directional electronic data signal bus 3634 that is inelectronic signal communication with industrial computer 3626 and DCS3628. DAQ 3624 has data storage capability to store past demand data andtrending data in a manner similar to DAQ 200 discussed in the foregoingdescription and shown in FIGS. 2 and 4. DAQ 3624 functions in the samemanner as DAQ 200 and, when combined with motor-feedback signals, sensorsignals and industrial computer 3626, provides a variable processcontrol system that is adaptive and which learns the process coolingdemand by historical trending as a function of date and time therebyeliminating or substantially minimizing system lead and lag.

HVAC systems typically utilize a plurality of pressure, temperature, airflow and humidity sensors which output sensor signals 3640. In somescenarios, these HVAC system sensors are pre-existing and are integratedwith control system 3620. Accordingly, these sensor signals 3640 areinputted into DAQ 3624 along with the vibration sensor signals 3642 andmotor-heat sensor signals 3644 which emanate from correspondingvibration and heat sensors on or within ECM 3602. The vibration sensorsignals 3642 represent sensed vibrations resulting from rotation of fan3608. The motor-heat sensor signals 3644 represent the heat of the motorstator and the heat of the interior of motor 3602. All sensor outputsignals 3640, 3642 and 3644 are then further processed by industrialcomputer 3626. The power and motor control signals provided by theinverter of motor controller 3606 are also inputted into DAQ 3624 viabus 3630 and then routed to industrial computer 3626 for furtherprocessing in order to provide additional fan control, monitoring,supervision and integration with signals from DCS 3628. Motor controller3606 directly reads and monitors the poles of motor 3602 therebyeliminating a need for an encoder or specific motor feedback device.Motor controller 3606 always knows the direction of rotation andposition of the motor rotor about its axis which allows ECM 3602 torotate fan 3608 at variable speed and be programmed with different ramprates to accelerate and decelerate and hold at zero (0.0) RPM to preventwindmilling. In an alternate embodiment, the motor 3602 includes afeedback device. In one embodiment, the feedback device is an encoder.

In another embodiment, the motor 3602 is operated at a single speed.

Referring to FIGS. 35A and 35B, there is shown an HVAC system 3700 thatcomprises a modified version of the air-handling system of FIG. 30A andthe control system 3620 shown in FIG. 34. Direct-drive air handlingsystem 3710 comprises ECM 3602 that is shown in FIG. 34. Fan 3152 hasfan hub 3154 which is connected to motor shaft 3604. Fan 3152 rotateswithin fan stack 3160 which is attached to fan deck 3170. Fan 3152 waspreviously described herein and is shown in FIGS. 29 and 33. Rotation offan 3152 moves air through a bank of condenser coils 3174. The plenumvolume 3172 is shown below fan deck 3170 and allows a single axial fanto serve any shape array of condenser coils. Direct-drive centrifugalfan apparatus 3730 comprises an electrically commutated motor (ECM) (notshown) that is identical in construction to motor 3602 and includes arotatable shaft and an integrated motor controller (not shown). Controlsignals from DAQ 3624 are inputted into the integrated motor controllerof centrifugal fan apparatus 3730 via bi-directional electronic datasignal bus 3752. HVAC system 3700 further includes temperature,pressure, air-flow and humidity sensors 3760. The signals outputted bysensors 3760 are inputted into DAQ 3624 via wire or cable network 3780or via wireless system. Vibration sensor signals and motor-heat sensorsignals (not shown) from each ECM of air-handling system 3710 andcentrifugal fan apparatus 3730 are also inputted into DAQ 3624 via awiring or cable network (not shown). The vibration and motor-heatsensors of each ECM, DAQ 3624, industrial computer 3626, DCS 3628 andthe HVAC system sensors 3760 cooperate to provide additional monitoring,supervision and control. Existing HVAC system thermostats and weatherstations can be integrated into the system shown in FIG. 35A in order toallow this system to anticipate demand based on current weatherconditions and forecast data as well as trending and past demand datathat is stored in DAQ 3624.

Referring to FIG. 36, there is shown HVAC system 3800 that comprises thedirect-drive air handling systems 3150 and 3504 of FIG. 33, a controlsystem 3810 and temperature, pressure, air-flow and humidity sensors3840. Control system 3810 comprises a first variable frequency drive(VFD) 3820, data acquisition device (DAQ) 3822, industrial computer (IC)3824 and second VFD 3826. Control system 3810 further includesdistributed control system (DCS) 3828. First VFD 3820 controls motor 20of direct-drive air handling system 3150 and second VFD 3826 controlsmotor 20 of direct-drive air handling system 3504. First VFD 3820 is inelectronic signal communication with DAQ 3822 via bi-directionalelectronic data signal bus 3830. Second VFD 3826 is in electronic signalcommunication with DAQ 3822 via bi-directional electronic data signalbus 3831. DAQ 3822 is in electronic signal communication with industrialcomputer 3824 via bi-directional electronic data signal bus 3832.Industrial computer 3824 is in electronic signal communication with DCS3828 via bi-directional electronic data signal bus 3834. Temperature,pressure, humidity and air-flow sensors 3840 are in electronic signalcommunication with DAQ 3822 via wiring or cable network 3850 or via awireless system. Rotation of the fans 3152 and 3510 move air through thebank of condenser coils 3174. DAQ 3822 functions in the same manner asDAQ 200 and, when combined with motor-feedback signals, sensor signalsand industrial computer 3824, provides a variable process control systemthat is adaptive and which learns the process cooling demand byhistorical trending as a function of date and time thereby eliminatingor substantially minimizing system lead and lag. Furthermore, thevibration and motor-heat sensor signals (not shown) from each motor 20cooperate with DAQ 3822, industrial computer 3824, DCS 3828 and HVACsystem sensors 3840 to provide additional monitoring, supervision andcontrol. Existing HVAC system thermostats and weather stations can beintegrated into the system shown in FIG. 36 in order to allow thissystem to anticipate demand based on current weather conditions andforecast data as well as trending and past demand data that is stored inDAQ 3822.

In another embodiment, the data acquisition devices (DAQ) of the controlsystems described above are programmed to implement the method foroptimizing energy in an HVAC system that is described in internationalapplication no. PCT/US2012/028007 entitled “Systems And Methods ForOptimizing Energy And Resource Management For Building Systems” andpublished under International Publication No. WO 2012/122234. Thedisclosures of the aforesaid international application no.PCT/US2012/028007 and International Publication No. WO 2012/122234 arehereby incorporated by reference.

In another embodiment, the data acquisition devices (DAQ) of the controlsystems described above are programmed to implement the method fordetermining parameters for controlling a HVAC system that is describedin U.S application Ser. No. 13/816,325 entitled “Methods for DeterminingParameters for Controlling An HVAC System” and published under PatentApplication Publication No. US 2013/0144444. The disclosures of U.S.application Ser. No. 13/816,325 and publication no. US 2013/0144444 arehereby incorporated by reference.

In another embodiment, the data acquisition devices (DAQ) of the controlsystems described above are programmed to implement the method forcontrolling HVAC systems using set-point trajectories that are describedin U.S. application Ser. No. 13/324,140 entitled “Method for ControllingHVAC Systems Using Set-Point Trajectories” and published under PatentApplication Publication No. US 2013/0151013. The disclosures of theaforesaid U.S. application Ser. No. 13/324,140 and Publication No. US2013/0151013 are hereby incorporated by reference.

In other embodiments, the motor in the direct-drive air-handing systemis a permanent magnet motor that can be configured with either the fanbeing rotated by the motor shaft or an “inside-out motor” wherein thestator is connected to the fan hub and the rotor is stationary, such asin a ceiling fan application, or in the alternate embodiment of thesystem shown in FIG. 31B described in the foregoing description. Otherapplications include direct drive ceiling fans, furnace blowers, blastfurnace fans, mechanical mixers and chillers, condenser coolers andexhaust fans, such as the type used in tunnels.

While the foregoing description is exemplary of the present invention,those of ordinary skill in the relevant arts will recognize the manyvariations, alterations, modifications, substitutions and the like arereadily possible, especially in light of this description, theaccompanying drawings and the claims drawn hereto. In any case, becausethe scope of the invention is much broader than any particularembodiment, the foregoing detailed description should not be construedas a limitation of the present invention, which is limited only by theclaims appended hereto.

What is claimed is:
 1. A heating ventilation and air-conditioning systemcomprising: a fan deck; a plenum volume below the fan deck; a bank ofcondenser coils below the fan deck; a first direct-drive air-handlingsystem comprising: a fan stack attached to the fan deck, a firstvariable speed, load bearing permanent magnet motor comprising a casinghaving an interior, a stator and rotor located in the interior of thecasing, and a rotatable shaft, a first fan directly connected to therotatable shaft such that the first fan is solely supported by the firstmotor, wherein the first fan is rotatable within the fan stack, saidfirst motor comprising a bearing system for bearing fan loads andenabling the first motor to rotate the first fan in a forward directionor reverse direction, wherein rotation of the first fan causes air-flowthrough the bank of condenser coils, the bearing system being configuredto absorb the thrust loads resulting from the weight of the first fanand the airflow produced by rotation of the first fan, oppose the radialloads at the thrust end of the rotatable shaft, and oppose the reversethrust loads resulting from reverse rotation of the first fan and yawloads; a first device to generate electrical signals that cause rotationof the rotatable shaft of the first motor at a predetermined motor RPMand rotational direction in order to rotate the first fan, the firstdevice having a signal input for receiving control signals thatdetermine the motor RPM and rotational direction; a plurality ofpressure, temperature, airflow and humidity sensors located in theplenum that provide sensor output signals; at least one vibration sensorto provide vibration sensor output signals that represent sensedvibrations resulting from rotation of the first fan; and a digitalacquisition device in electronic signal communication with the firstdevice and all of the sensors, wherein the digital acquisition device isconfigured to process the signals provided by the pressure, temperature,airflow, humidity and vibrations sensors and, in response, output thecontrol signals for input into the first device.
 2. The heatingventilation and air-conditioning system according to claim 1 wherein thefirst motor includes at least one temperature sensor to measure thetemperature of the interior of the casing and provide temperature sensoroutput signals that represent the measured temperature of the interiorof the casing, wherein the digital acquisition device is in electronicsignal communication with the temperature sensor and is configured toprocess the temperature sensor output signals.
 3. The heatingventilation and air-conditioning system according to claim 1 wherein thefirst motor includes at least one temperature sensor positioned on thestator to measure the temperature of the stator and provide temperaturesensor output signals that represent the measured temperature of thestator, wherein the digital acquisition device is in electronic signalcommunication with the temperature sensor and is configured to processthe temperature sensor output signals.
 4. The heating ventilation andair-conditioning system according to claim 1 wherein the first device togenerate electrical signals comprises a variable frequency drive device.5. The heating ventilation and air-conditioning system according toclaim 1 wherein the first device to generate electrical signalscomprises a variable speed drive device.
 6. The heating ventilation andair-conditioning system according to claim 1 wherein the first motor isoriented such that the rotational shaft of the first motor issubstantially vertical.
 7. The heating ventilation and air-conditioningsystem according to claim 1 wherein the first motor is oriented suchthat the rotational shaft of the motor is substantially horizontal. 8.The heating ventilation and air-conditioning system according to claim 1wherein the first motor is oriented such that the rotational shaft is atan angle.
 9. The heating ventilation and air-conditioning systemaccording to claim 1 further comprising a second direct-drive airhandling system including: a second variable speed, load bearingpermanent magnet motor comprising a casing having an interior, a statorand rotor located in the interior of the casing, and a rotatable shaft;a second fan directly connected to the rotatable shaft of the secondmotor such that the second fan is solely supported by the second motor;wherein the second motor comprises a bearing system for bearing fanloads and enabling the second motor to rotate the second fan in aforward direction or reverse direction, wherein rotation of the secondfan causes air-flow through the bank of condenser coils, the bearingsystem configured to absorb the thrust loads resulting from the weightof the second fan and the airflow produced by rotation of the secondfan, oppose the radial loads at the thrust end of the rotatable shaft,and oppose the reverse thrust loads resulting from reverse rotation ofthe second fan and yaw loads; a second device to generate electricalsignals that cause rotation of the rotatable shaft of the second motorin accordance with a predetermined speed and rotational direction inorder to rotate the second fan, the second device having a controlsignal input for receiving control signals that determine motor RPM androtational direction; at least one additional vibration sensor toprovide additional vibration sensor output signals that represent sensedvibrations resulting from rotation of the second fan; and said digitalacquisition device being in electronic signal communication with thesecond device and all of the sensors including the at least oneadditional vibration sensor, wherein the digital acquisition device isfurther configured to process the signals provided by all of the sensorsand, in response, output the control signals for input into the controlsignal input of the second device.
 10. The heating ventilation andair-conditioning system according to claim 9 further comprising at leastone temperature sensor to measure the temperature within the interior ofthe casing of the second motor and provide temperature sensor outputsignals representing the temperature within the casing of the secondmotor, wherein the digital acquisition device is in electroniccommunication with the at least one temperature sensor and is configuredto process the temperature sensor output signals representing thetemperature within the casing of the second motor; and at least onetemperature sensor positioned on the stator of the second motor tomeasure the temperature of the stator of the second motor and providetemperature sensor output signals that represent the measuredtemperature of the stator of the second motor, wherein the digitalacquisition device is in electronic signal communication with thetemperature sensor and is configured to process the temperature sensoroutput signals representing the temperature of the stator of the secondmotor.
 11. The heating ventilation and air-conditioning system accordingto claim 1 further comprising: an industrial computer in electronicsignal communication with the data acquisition device; and a distributedcontrol system in electrical signal communication with the industrialcomputer and configured to generate a signal, for input into theindustrial computer, that indicates specific cooling requirements, thedistributed control system being further configured to output alert orevent signals to notify operators and to receive data inputted by theoperators.
 12. The heating ventilation and air-conditioning systemaccording to claim 1 wherein the data acquisition device is programmedto implement a method for optimizing building energy usage.